i.   Water moves to the upper parts of the plants through the xylem by a pull, this pull is due to the process of———————————————

ii. The process by which water enters from the soil into the roots of the plant is ———————————-

iii. When iodine solution is applied to starch, it turns——————————————

iv. The network of thread like structure in rhizopus is called————————————-

v. Ginger is an example of underground——————————————-                                                                                             .


(i-transpiration )(ii- osmosis)(iii- blue )(iv-hyphae )(v- stem)




(i)           The movement of water molecules through a selectively permeable membrane from an area of higher concentration to an area of lower concentration is called:

(a) Conduction (b) Diffusion (c) Evaporation (d) Osmosis

(ii) Fruit is formed from:

(a) Overy (b)Ovule (c) Stem (d) Leaves

(iii) Endosperm is present in:

(a) Anther (b) Xylem (c) Stigma (d) Stigma

(iv) Which is not a part of the embryo?

(a) Cotyledon (b) Radicle (c) Pedicel (d) Plumule

(v) Which statement is not true for insectivorous plants?

(a) Chlorophyll is not present (b) Unable to make glucose
(c) Capture insects through roots
(d) Utilize their nitrogenous needs from insects

(vi)   Which part of the plant is called the food factory?

(a)   Fruit

(b)   Leaves

(c)   Root

(d) Stem



(i-d )(ii-a )(iii-d )(iv-c )(v-d )(vi-b )




SHORT QUESTION No.i                                                              Differentiate between self and cross pollination.

ANSWER:                                                                                              SELF- POLLINATION                                                                               If the pollens from another flower fall on the stigma of same flower or another flower of the same plant is called self-pollination.                                                                                  CROSS POLLINATION:                                                                              If the pollens from the flower of one plant fall on the stigma of flower of another plant is called cross-pollination.

SHORT QUESTION No.ii                                                            Why is a butterfly attracted towards a flower?

ANSWER:                                                                                           Petals have a beautiful colours, fragrance and nectar which attract insects and butterfly.

SHORT QUESTION No.iii                                                           Explain the possible directions for the transport of food in a plant.

ANSWER:                                                                                            The food may be transported by phloem in any direction within the plant. It may be carried upward, downward, and even laterally.

SHORT QUESTION No.iv                                                              Stomata mostly occur in the epidermis of the leaf. How is it helpful for the plant?

ANSWER:                                                                                                        Carbon dioxide can enter and oxygen and water vapours leave through these stomata.

SHORT QUESTION No.v                                                                   What is the role of chlorophyll in photosynthesis?

ANSWER:                                                                                     Chlorophyll can absorb sunlight and convert it into chemical energy in then used to combine carbon dioxide and H 0 to make food. This energy is converted into glucose molecules.

SHORT QUESTION                                                                               What is the difference between auto-trophs and hetero-trophs?

ANSWER:                                                                                                                  AUTO- TROPHS:                                                                                                        (1) The plants which can prepare their own food by process of photosynthesis are called auto-trophs.                                                                          (2) These plants have chlorophyll.                                                                            (3) Most green plants are auto-trophs.                                                              HETERO- TROPHS:                                                                                            (1) The plants which cannot prepare their own food.
(2) These plants have no chlorophyll.                                                                                  (3) Example: Cucuta.

SHORT QUESTION No.vii                                                                                    What is the difference between parasites and sapro-trophs?

ANSWER:                                                                                                     PARASITES:                                                                                                  Organisms which get their food from other living animals are called parasites.                                                                                 EXAMPLE: Cucuta.                                                                    SAPROTROPHS:                                                                                       Organisms which get their food from dead organic matter are called sapro-trophs.                                                                                            EXAMPLE: Mushrooms.




Explain the role of a flower in cross-pollination?


A flower has following parts;

(1) Calyx
(2) Corolla

(3) Androecia
(4) Gynacium

The butterflies and other insects are attracted to the flower due to corolla. When these insects visit a flower, pollen grains from the make part of the flower are attached with their body. When they visit another flower, pollen grains fall on the female part (carpal) of flower.

In this way, an important process of sexual reproduction is accomplished. This process is called cross-pollination.


Where and how are fruit and seeds formed?


As a result of pollination, the pollen reaches the stigma of the flower. Its outer wall ruptures and a tube grows out which is called pollen tube. The pollen tube has two male gametes in it.

Female gamete which is called ovum or egg is present in the ovule. When the pollen tube reaches the ovule, it releases both the male gametes. One male gamete fuses with the egg


Explain the structure of a gram seed?


The seed has following basic parts:

(i) TESTA:

This is the outer hard covering of the seed which protects their internal

(ii) TEGMEN:

It is membrane present beneath the testa for the protection of embryo.


In some seed, endosperm stores food which is used in germination of seed.

(iv) EMBRYO:

This is the most important part of seed. This is tiny plant whose parts grow to form a
new plant. The embryo has following parts.

(a)     Plumule: this is the part of embryo which forms the shoot, that is stem and leaves.

(b)     Radical: this part of the embryo develops into root of plant.

(c)      Cotyledons: they may be one of two in number. These receive the food from the endosperm and supply it to the growing tiny plant.


How is the structure of a leaf adapted to photosynthesis?


a)     Most leaves are flat to absorb enough light effectively.

b)    They are thin so that carbon dioxide and light can reach inner cells easily.

c)     They have large number of stomata in the lower surface (lower epidermis). Carbon
dioxide can enter and oxygen and water vapours leave through stomata.

d)    They have thick layer of mesophyll cells in middle. These cells have chloroplasts which
contain chlorophyll. Mesophyll cells make food for the plants by photosynthesis.

They have a rich network of veins. They carry water to photosynthesizing cells and glucose away from them. Therefore it is rightly said that leaf is a good factory.


Prove with the help of an experiment that chlorophyll is necessary for photosynthesis?


(1) Take a variegated leaf (partially white and green). Make a drawing of it, showing the chlorophyll.

(2) Half fill one 250 ml beaker with water.

(3) Place the variegated leaf in the beaker and boil it for about 5 minutes
(4) Take one 100ml test tube and half fill it with 70% alcohol.

(5) With a forceps and tongs remove the boiled leaf from the water and transfer it to alcohol in the smaller (100ml) test tube (containing the alcohol and the leaf) in a boiling water bath.

(6) Boil the alcohol until the leaf loses its chlorophyll and alcohol turns green (chlorophyll is soluble in alcohol but not in water).

(7) Using forceps or tongs transfer colourless leaf first to a beaker containing boiling water to make it soft and then to a Petri dish.

(8) Put drops of iodine solution on the leaf until iodine has come into contact with the entire leaf.

You will see green part of the leaf turns blue, indicating the presence of starch. The white part becomes iodine-coloured (brown) indicating the absence of starch. This experiment shows that chlorophyll is necessary for photosynthesis.


What is the importance of photosynthesis for living organisms?


Plants convert excess sugar (glucose) into starch, proteins and fats and store it in their stems, roots, fruit, seeds and leaves. These parts of plants may be eaten by animals which in turn may be eaten by other animals. Photosynthesis, therefore, is the process which provides food and energy to all life forms earth.

Oxygen is produced during photosynthesis which is used for respiration by all living organisms. Similarly, carbon dioxide is produced during respiration is used by plants during photosynthesis. Due to these processes the ratio of oxygen and carbon dioxide is maintained in the air.



(i)   The saliva helps in digestion of——————-

(ii)    The——————————–present in the stomach kills the harmful bacteria.

(iii)   The excretory organs of human body are skin, lungs and—————————-

(iv) The central nervous system of man consists of —————————— and spinal cord.

(v)   Our tongue can detect four tastes namely sweet, salty, ——————— and ———————-.

(vi) The skin is a sense organ which detects heat, cold, ——— and pressure.

(vii) The sensory cells of ——————- are stimulated by the light and send nerve message from

ANSWERS: (i-carbohydrates) (ii-hydrochloric acid HCl )(iii-kidneys )(iv-brain )(v-bitter + sour )(vi-pain ) (vii-retina+ eye )



(i)Bile is secreted in pancreas.

  • The omnivores feed on vegetables, fruits, seeds and meat.
  • The oxygenated blood from lungs reaches to heart by pulmonary veins.
  • There are two kidneys present in the chest of human body.
  • Aorta receives blood from the whole body.
  • Nerve is the basic unit of structure and function of nervous system.
  • The most sensitive layer of the eye ball is called retina.
  • The outer layer of skin is the sensitive part of the skin.


ANSWERS: (i-F)(ii-T)(iii-T)(iv-F)(v-F)(vi-F ) (vii-T)(viii- F)



Carbohydrates are digested in

(a)   Mouth and small intestine

(b)   Mouth and stomach

(c) Mouth and large intestine

(d)     Stomach and small intestine

(ii)    The function of large intestine is to

(a)   Digest fats and proteins

(b)   Digest carbohydrates and salts

(c)   Absorb water and salts

(d)   Absorb carbohydrates and salts

(iii)   Which part of the brain controls the heart beat and breathing?

(a) Cerebrum (b) Cerebellum

(c) Medulla    (d) Midbrain

(iv) Taste buds for bitter taste are present

(a)   On the tip of the tongue

(b) On the sides of the tongue

(c)   At the back of the tongue

(d) On the tongue

(v)   Circulation of blood in heart is due to

(a)   Dilation of atrium    (b)contraction of atrium

(c) Dilation of venticle    (d) contraction of ventricle

ANSWERS: (i-a)(ii-c)(iii-c)(iv-c)(v-b)



SHORT QUESTION No.i                                                                    Why digestion of food is necessary?

ANSWER:                                                                                         Our food basically consists of a few important compounds. These are carbohydrates, proteins and fats. All these compounds are in the form of very large molecules and cannot be
taken into the cells of the body until they are broken down into smaller molecules.                                                                           The broken down food molecules enter the cell where they take part in supplying energy to the cells.

SHORT QUESTION No.ii                                                                    In which part of alimentary canal food digests completely?

ANSWER:                                                                                      Food completely digests in small intestine.

SHORT QUESTION No.iii                                                          Describe the importance of body skeleton?

ANSWER:                                                                                          Body skeleton is very important because it gives shape to the body. It provides support and protect different organs of body.

SHORT QUESTION No.iv                                                                Write down the names of important parts of respiratory system?

ANSWER:                                                                                   HUMAN RESPIRATORY SYSTEM                                         Human respiratory system consists of nose, pharynx, trachea, bronchi and lungs.                                              

SHORT QUESTION No.v                                                                What is the role of reproductive system of human body?                            

ANSWER:                                                                               Reproductive system of any organism including man is meant for the continuity of race. It ensures the survival of the species while producing off-spring.                                                             The transmission of characteristics from generation after generation are carried through this system.                            

SHORT QUESTION No. vi                                                             Name any sense organ which contains receptors of chemical stimuli?

ANSWER:                                                                                       Nose is a sense organ which contains receptors of chemical stimuli.                      

SHORT QUESTION No.vii                                                            What part of the ear helps the balance?

ANSWER:                                                                                       Inner part of the ear helps the balance.

SHORT QUESTION No.viii                                                        Describe the two defects of vision?

ANSWER:                                                                                   (a)SHORT-SIGHTEDNESS                                                         Short- sightedness is also known as Myopia. In this defect short- sighted person can see near objects. But the distant objects look blurring.                                                                                                       (b)LONG-SIGHTEDNESS                                                                            In this defect long- sighted person can see distant objects clearly. But the near objects look blurring.                                         

QUESTION No.05(i)                                                                       Explain the following nerve & neuron?

ANSWER:                                                                                     NERVE: Nerves are white, tough and string like structures. There are two types of nerves;                                                                              a.Sensory nerves: carry messages from organs i.e. eyes, ears, nose etc. to control system.                                                                 b.Motor nerves: carry messages from central nervous system to muscles and glands.                                                                  NEURON: Neuron is a basic unit of structure and function of nervous system. Brain spinal cord and nerves are made up of neuron.

QUESTION No.05(ii)                                                                          Explain the sensory nerve and motor nerve?

ANSWER:                                                                                                  1-Sensory nerves: carry messages from organs i.e. eyes, ears, nose etc. to control system.                                                                                  2-Motor nerves: carry messages from central nervous system to muscles and glands.

SHORT QUESTION No. 05(iii)                                                              Explain the following cerebrum & neuron?

ANSWER:                                                                                      CEREBRUM: cerebrum is the part of fore-brain. It is responsible for conscious, thought, language and personality.                                      CEREBELLUM: The area of hind brain which controls balance and muscular coordination is called cerebellum.

LONG QUESTION No.06                                                                              Write down the effects of noise pollution?

ANSWER:                                                                                            NOISE POLLUTION:                                                                    Unwanted or unpleasant sound that is often very loud is called noise. When noise becomes unbearable then it is called noise pollution.                                                                                           EFFECTS of NOISE POLLUTION:                                                      (1) It is very difficult for people to relax and think properly in noise.
(2) Noise makes them often irritable or bad tempered.                                                            (3) Constant noise can also cause fatigue and headache.                                                    (4) Noise can cause high blood pressure and may disturb our digestive system.                                                                                            (5) Excessive noise can make people work less safely, suffer from stress, lose their hearing and eventually become deaf.                                                                   (6) Loud noise of a long duration also damage hearing permanently.

LONG QUESTION No.07                                                                      Describe briefly structure of eye with diagram and label its different parts?

ANSWER:                                                                                                   The eye is the organ of sight. The human eye consists of an eye-ball. The wall of the eye- ball consists of three layers. The front of the eye-ball is transparent is called the cornea. Beneath the cornea the free edge of the middle layer forms iris, which is coloured part of the eye which has ability to contract and relax. In the center of the iris is an opening-pupil.                                                                                               Just behind the pupil, which help to focus the light. The inner layer of the eye-ball is called retina. It receives images of objects focused by lens which we see. The eye is connected to the brain by the optic nerve.

LONG QUESTION No.08                                                                      How and where absorption of food takes place?

ANSWER:                                                                                                    In small intestine food is also mixed with digestive juice from the pancreas and gallbladder. This secretion are called pancreatic juice and bile.                                                                                                         It completely digests carbohydrates, proteins and fats. This is followed by the absorption of digested food into the blood vessels present on the inner surface of the wall of intestine from where it is distributed throughout the body via lever.                                                                                                                The part of the food which is mot digested in the intestine is called undigested food. This undigested part of food passes into the large intestine. Most of the water and salts are reabsorbed into the blood vessels present in the wall of large intestine.



LONG QUESTION No.10                                                                               How parasites and symbionts get their food from?

ANSWER:                                                                                           PARASITES: These are the animals which get food from other living animal. They absorb their food from their host.                                                      EXAMPE: Leech, mosquito and lice etc.                                    SYMBIONTS: Animals which live together in a mutually beneficial relationship. They provide food and protection to each other. They are so dependent on each other that cannot exist independently,                                                                EXAMPLE: Termite eats wood as food but single celled tiny animal live in its intestine and digests the food.

LONG QUESTION No.11                                                                          Describe structure of heart and circulation of blood with the help of diagram?

ANSWER:                                                                                                STRUCTURE of HEART:                                                            Human heart has four chambers. Two upper chambers of heart are small and thin walled are called “atria”. The two lower parts are relatively large and thick walled are called “ventricles”.                                                              Valves are present between the atria and ventricles. These valves ensure that blood flows easily from atria into the ventricles and not in the opposite direction.                            CIRCULATION of BLOOD in the BODY: Heart acts as double pump. It can be divided into two parts; right side and left side.                                                                                                                               Left side consists of left auricle and left ventricle. Right side has right auricle and right ventricle.
In the right auricle, blood from the whole body comes back through two large veins venacava. It has less amount of oxygen. When right auricle contracts blood it is pushed into right ventricle.
From this chamber, the blood is pumped out through pulmonary artery to the lungs. In the lungs, the blood collects oxygen from the inhaled air and gives up its carbon dioxide. This oxygenated (rich in oxygen) blood from the lungs then returns to the left auricle through pulmonary veins. When left auricle contracts, it is pushed into the left ventricle.                                                                                                     From this chamber of the heart, the blood through a large artery, Aorta is carried to the upper parts and to the lower side that is lever, digestive system, kidneys and legs etc.

LONG QUESTION No.12                                                                       Describe structure of blood and its important functions?

ANSWER:                                                                                                   Blood is a red fluid in which red cells white blood cells and platelets are present in a yellowish white liquid which is called plasma.                                                                                                Blood plasma consists of water, digested food material, carbon dioxide, hormones and waste substances.                                                    Red blood cells contain hemoglobin which transports oxygen. Function of white blood cells is to defend the body and destroy them. They engulf the bacteria which enter in the body and destroy them.                                                                                    The function of platelets is to clot the blood in case of injuries.                                      

LONG QUESTION No.13                                                                          Draw a diagram of excretory system and label its parts?

ANSWER: look on book



(i) Light, water, soil and temperature are——————— factors of environment.

(ii)Populations living together at the same place constitute a —————————–

(iii)The main source of energy is ———————–

(iv) Each plant or an animal in a food chain is called a —————————-

(v) The lowest level in a food chain is occupied by———————————

ANSWERS: (i-abiotic)(ii-community)(iii-Sun)(iv-link)(v-producers)



(i)The type of environment an organism lives in is called

(a) Ecosystem             (b) Habitat                                                          (c) Community     (d) Population

(ii) Herbivores are                                                                      (a) Primary consumers                (b) Secondary consumers                  (c) Tertiary consumers (d) Omnivores

(iii) Animals are                                                                             (a) Producers        (b) Consumers                                               (c) Decomposers (d) Autotrophs

(iv) All feeding relationships in an-ecosystem are expressed by                                                                              (a)Food pyramid (b) Food chain                                                        (c) Food web (d)Energy flow

(v) The topmost level in a food pyrarnid is generally occupied by                                                                          (a) Primary consumers (b)Secondary consumers (c) Tertiary consumers (d) Producers

ANSWERS: (i-b)(ii-a)(iii-b)(iv-c)(v-c)





SHORT QUESTION No.3                                                                           Define the following:                                                                                   (1) community (2) ecosystem (3) population?

ANSWER:                                                                                                         (1)        COMMUNITY:                                                                                  Different species or populations living together and interacting with one another constitute a community.                                                                            (2)   ECOSYSTEM: System of communities interacting with the environment is called ecosystem.                                                                                    (3)          All members of a species living in a habitant are called population.

LONG QUESTION No.04                                                                    Describe briefly flow of energy in an ecosystem?

ANSWER:                                                                                                   Like all other systems, whether natural or artificial, energy is required to maintain an ecosystem. The sun is the main source of energy. Sunlight is used by plants to make food. This food is used by the plants themselves and also by all other living organisms.                                                                                                             Without plants, humans and all other animals would starve to death. This is because they cannot make their own food. The only way animals can obtain energy is by eating or consuming, plants of other animals. Animals are called consumers while plants are called producers.

LONG QUESTION No.05                                                                            Write a note a balance in nature?

ANSWER:                                                                                                Under normal conditions natural ecosystems maintain equilibrium between plants and animals and their non-living environment. We call this as “balance in nature”                                                                                                      Whenever this equilibrium is disturbed, the whole ecosystem is disturbed. An ecosystem has the ability to withstand changes of low magnitude and may return to its original state.
However, if disturbance is large, the ecosystem may not be able to absorb it and consequently, bear irreparable damages.



(i) The branch of biology which deals with the study heredity'” arid variations is—————————–
(ii)Thin membrane surrounding the nucleus is known as——————-
(iii) Small rounded body called—————————————–is present in the nucleus of cell.
(iv) Two chromatids of chromosome are attached with———————
(v)——————— is a unit of inheritance.
ANSWERS: (i-genetics)(ii-nuclear membrane)(iii-nucleoius )                       (iv-centromere)(v-gene)




(i) Transmission of characters from parents to their offspring is caned genetics
(ii) Chromosome is made of DNA.
(iii) Genes are arranged on chromosomes in a linear order.
(iv) Body (somatic) cells are concerned with reproduction.
(v) DNA is a unit of inheritance.
ANSWERS: (i-F)(ii-F)(iii-T)(iv-F)(v-F)



(i)Chemically gene is made up of

(a)     Protein       (b)     DNA (c) Protein and DNA

(ii) Number of chromosomes in somatic (body) cells of human being are

(a)8           (b)14             (c)23       (d)46

(iii) Chromosomes are made up of

(a) Protein (b)      DNA (c) Protein and DNA

ANSWERS: (i-b)     (ii-d)         (iii-c)





SHORT QUESTION No.i                                                                                What is gene?

ANSWER:                                                                                                           Gene is the unit of inheritance. It is a short length of DNA molecules in chromosome. It controls a particular character like hair, colour and height etc.

SHORT QUESTION No.ii                                                                            Write down difference between chromosome and chromotid?

ANSWER:                                                                                                    Each chromosome is seen to be made up of two similar strands called atids and these chromatids are attached at same centromere to form a chromosome.

SHORT QUESTION No.iii                                                                                 Define the term of genetic code?

ANSWER:                                                                                                                 DNA is the genetic material. DNA stores genetic information in the sequence of its nucleotides in a linear order and is responsible for physical structure and functioning of the body. The information is stored in the form of code known as genetic code.

SHORT QUESTION No.05                                                                                                                       Describe the structure of nucleus?

ANSWER:                                                                                                             The nucleus is the most important component of a living cell. The nucleus is encloses in a membrane called nucleus membrane and contains semi-fluid material called nucleoplasm.                                                                                    The nuclear membrane has minute pores which allow the flow of materials between the nucleus and cytoplasm. The nucleus densely stain round body

QUESTION No.06                                                                                                    Describe the structure of DNA?

ANSWER: p:53



(i) An atom contains ——————————————–type of fundamental particles.
(ii) The charge present on an electron is —————————–and that present on a proton is————————————–
(iii) Protons and neutrons are present in the ———————————-of an atom.
(iv) The paths around which the electrons revolve are known as —————————
(v) The outermost shell of oxygen atom has six electrons, its valency will be——————————
(vi) Hydrogen element has ——————————————-isotopes.
(vii) The nucleus of nitrogen atom contains 7 protons, the number of electrons present in its L-shell will be———————————————-
(viii) The total number of neutrons and protons present in the nucleus of an atom is ——————————–called its———————————-
(ix) An atom has 20 neutrons and 20 electrons, it will also have———————–protons present on it.
(x) Isotopes of an element have the same number of ————————————-, but different number of——————————-
ANSWERS: (i-3)(ii-negative+ positive)(iii-nucleus)(iv-orbit)(v–2)(vi-3 ) (vii-5)(viii-atomic mass ) (ix-20)(x-electrons or protons )



(i)The number of electrons and protons in an atom is always the same

(ii) The amounts of all the three isotopes in hydrogen are the same.

(iii) An atom of carbon contains 6 electrons, 6 neutrons and 7 protons.

(iv) Different atoms always combine in the same ratio to form a chemical compound.

ANSWERS: (i-T)(ii-F)(iii-F)(iv-T)



(i)An atom which does not have a neutron

(a) Beryllium (b) Helium (c) Protium (d) Deutrium

(ii) Atomic number of boron is 5. The number of electrons in its K-shell will be:

(a) 5                (b) 4              (c) 2             (d) 3

(iii) Which atom is represented by the following figure?

(a)    Lithium      (b) Beryllium    (c) Helium (d) Tritium

(iv) An atom has 8 electrons, 8 protons and 8 neutrons. What will mass?

(a) 8                 (b) 16               (c) 24            (d) 32

(v) Isotopes of an element have:

(a)    Same physical and chemical properties.

(b)     Different physical and chemical properties

(c)     Same physical properties but different chemical properties.

(d) Different physical properties but same chemical properties.

ANSWERS: (i-c)(ii-c)(iii-b)(iv-b)(v-d)




QUESTION No.04                                                                                                 What do you understand from the terms atomic number and atomic mass?

ANSWER:                                                                                                       A TOMIC NUMBER:                                                                                                 The number of protons present in the nucleus of an atom is called its atomic number or proton number and is represented by “Z”.                                                                                                    Each element has its own atomic number and it is different from the other elements.                                                                      Therefore, atomic number serves as a tool to identify elements.                                                                                             Hydrogen is the lightest element with one proton present in its nucleus. It is the only atom that does not have any neutron in its nucleus. Its atomic number is “l”. Helium atom has two protons present in its nucleus. Hence, its atomic number will be “2”. ATOMIC MASS:                                                                                    The total number of protons and neutrons present in the nucleus of an atom is called its atomic mass or mass number and is represented by “A”.

QUESTION No.05                                                                                 Hydrogen gas and chlorine gas combine in the presence of sunlight to form hydrogen chloride gas. Can you tell whether only prtium or all the isotopes of hydrogen will participate in this reaction?

ANSWER:                                                                                                     All the three isotopes of hydrogen will react with because isotopes of an element have similar chemical properties but their physical properties are different.



QUESTION No.07                                                                                       What are isotopes? How do the isotopes of an element differ and resemble to each other?

ANSWER:                                                                                                       ISOTOPES:                                                                                                          Atoms of an element having different atomic mass but same atomic number is called isotopes.                                                        The atoms of any element may have different atomic masses. This is because nuclei of these atoms may have the same number of protons but different number of neutrons.                                                                              For example, element of hydrogen comprises three kinds of atoms. The isotopes of an element have similar chemical properties but show different physical properties.

QUESTlON No.08                                                                                  Name any three atoms, which has the same number of electrons, protons and neutrons?

ANSWER:                                                                                                                                                                (1) Carbon
(2) Nitrogen
(3) Oxygen
(4) Neon                                                                                          have the same number of electrons, protons andneutrons.

SHORTQUESTION No.09                                                                                     An atom has one electron more than its protons. What will be the charge on it?

ANSWER:                                                                                                                   That atom which has one electron more than its protons, negative charge will be present in that atom.

CH: 6   P:



i-Oxygen supports the———————————————————-process.

ii-Oxygen is prepared in the laboratory by heating potassium chlorate in the presence of ————————————————-

iii-Hydrogen gas, in free state is found in ———————————————-

iv-Hydrogen reacts with ————————————————-to form water.

v-Corbon dioxide is produced during combustion and————————————

ANSWERS: (i-combustion)(ii-manganese dioxide)(iii-Sun)(iv-oxygen)(v-respiration)




(i)A constituent of fuel used in a space ship is:

(a)      Nitrogen (b) Chlorine (c) Oxygen (d) Bromine

(ii)The gas liberated by plants during day light is.


(a)Carbon dioxide (b) Oxygen (c) Sulpher (d) Hydrogen

(iii) Hydrogen gas was discovered by:

(a)Scheele (b) Robert Boyle (c) Cavendish (d) Van Halmont

(iv)The most abundanty found element in earth crust is:

(a) Hydrogen (b) Oxygen (c) Carbon (d) Aluminuim

(v) Percentage of carbon dioxide present in air by volume:

(a) 0.5% (b) 1% (c) 0.03% (d) 3%


ANSWERS: (i-c)(ii-b)(iii-c)(iv-b)(v-d)



1.The gas which support combustion.

2.The gas which burns with blue flame.

3.The gas liberated by plants in the absence of sunlight.

4.Metals combine with oxygen and produce.

a-Carbon dioxide




ANSWERS: (i-c)(ii-d)(iii-a)(iv-b)




SHORT QUESTION No.i                                                                                  Which compounds are used during the laboratory preparation of oxygen gas?

ANSWER:                                                                                                             Oxygen gas is prepared in the laboratory by heating potassium chlorate in a test tube is the presence of manganese dioxide.

SHORT QUESTION No.ii                                                                             State the properties of hydrogen gas?

ANSWER:                                                                                                                (1)         Hydrogen gas is a colourless, odourless and tasteless gas.                                                                                                          (2)          It is sparingly soluble in water.                                                   (3)       It is the lightest of all elements.                                          

SHORT QUESTION No.iii                                                                                      What are the natural sources of carbon dioxide?

ANSWER:                                                                                                             (i)     Carbon dioxide gas was discovered by Van Helmont.                           (ii) It is also found in volcanic gases.                                                 (iii)      Most of carbon dioxide present in air is produced in respiration and combustion processes.

SHORT QUESTION No.iv                                                                                    What is the difference between the process of respiration in plants and human beings during the day light?

ANSWER:                                                                                                                 During day human beings used oxygen and carbon dioxide but plants use carbon dioxide and give by process of photosynthesis.

SHORT QUESTION No.v                                                                                  What is dry ice? Give its uses?

ANSWER:                                                                                                                                    (1) Carbon dioxide is converted into dry ice at -180°C.                                    (2) Dry ice is used for cooling in ice cream boxes and for the preservation of other eatables.

QUESTION No.5                                                                              Describe the laboratory preparation of hydrogen gas?

ANSWER:                                                                                                                        An English chemist Canvendish in (766AD) discovered hydrogen gas. lavoisr named it hydrogen which means “water producer” in Greek language. In laboratory, Hydrogen gas is prepared by the reaction of hydrochloric acid or salphuric acid with zinc metal.                                                                                    Hydrochloric acid + zinc—->Zinc Chloride+ Hydrogen gas                                                                                                               Add a few pieces of zinc metal in a round bottom flask fitted with a thistle found and a delivery tube. Place the other end of the delivery tube under a gas jar. Hydrogen gas involved is collected in the gas jar by the downward displacement of water.        

SHORT QUESTION No.06                                                                                       What are the uses of hydrogen gas?

ANSWER:                                                                                                   Hydrogen is used in the preparation of fertilizers.
(2) It is used as a fuel in rockets.                                                                           (3) It is failed in metrological balloons since, it is lighter than air.                                                                                                                               (4)It is used in the preparation of Banaspati ghee from vegetable like sunflower oil margarine from palm oil.

QUESTION No.07                                                                                                 How is oxygen gas prepared in the laboratory?

ANSWER:                                                                                                            Oxygen gas is prepared in the laboratory by heating potassium chlorate in a test tube is the presence of manganese dioxide. The test tube is fitted with a delivery tube through a cork.                                                                             The oxygen involved in this reaction is passed through the delivery tube to a air jar full of water placed on a beehive shelves in a water tube. Oxygen is collected in the jar by the down ward displacement of water.




(i)Water has covered ——————————————-percent of earth’s surface.

(ii)Human body contains ——————————————percent water, by mass.

(iii) Boiling point of water is ———————————-while its freezing point is———————————–

(iv) Most of the germs present in water are killed when it is boiled for———————————————– hours.

(v)Fertilizers, industrial wastes and animal wastes are the main causes of—————————–

ANSWERS: (i-71%)(ii-65 to 75)(iii-100 C+0 C)(iv-15 to 30)(v-water pollution)



(i)Which physical state of water do the clouds represent?

(a) Solid (b) Liquid (c) Gas (d) Vapours

(ii) Which method is applied for the removal of suspended impurities?

(a) Boiling (b) Filtration (c) Aeration (d) Decantation

(iii) Compounds which can cause temporary hardness of water are:

(a) Carbonates of calcium arid magnesium

(b)    Bicarbonates of calcium and magnesium

(c)    Sulphates of calcium and magnesium

(d)    Chlorides of calcium and magnesium

(iv) Clark’s method is applied

(a) For removal of water pollution

(b)    For removal of temporary hardness of water

(c)    For removal of permanent hardness of water

(d)    For removal of water logging and salinity

(v) Gypsum or calcium sulphate is used

(a) to remove impurities present in water

(b) to remove hardness of water

(c) to eradicate water logging

(d) to eradicate salinity

ANSWERS: (i-c)(ii-b)(iii-b)(iv-b)(v-d)





Describe the methods used for the removal of impurities present in water?

ANSWER:                                                                                                                    Following methods are used to of impurities present in water;                                                                                                                (i) FILTRATION:                                                                                                     Impure water is passed through filter paper place in a funnel. Insoluble salts and suspended solid particles ate left on the filter paper whereas the clear water is obtained as filtrate.                                                                                          (ii) USES OF POTASH ALUM:                                                                              Take water in a container and add some potash alum in it. Sand, clay and other insoluble impurities will settle down at the bottom.                                                                                              (iii)          BOILING:                                                                                                      Germs, bacteria and other microorganisms present in water may be killed by boiling it in a large container for 15 to 30 minutes.                                                                                                                       (iv)          CHLORINATION:                                                                                             Water supplied for domestic purposes is usually mixed with liquid chlorine to kill germs.                                                                                                            (V) AERATION:                                                                                                                  Aeration of water in the presence of sunlight, heat and air kills most of the germs nrpc;pnt in it.                                                                                           

QUESTION No.06                                                                                         Write down the methods used for the removal of temporary hardness of water?                                                                                                                    

ANSWER:                                                                                                                    Temporary hardness of water is removed by boiling. This process converts soluble bicarbonates of calcium and magnesium into their insoluble carbonates.                                                    These carbonates settle down after some time and can easily be removed by decantation. Temporary hardness of water can also be removed by reacting it with limewater (calcium hydro oxide) soluble bicarbonates, in this reaction are converted into insoluble carbonates, which can be removed, by filtration or decantation.

SHORT QUESTION No.3-i                                                                                    What meant by temporary hardness of water?

ANSWER:                                                                                                           Water that contains bicarbonates of calcium and magnesium is called temporary hard water.

SHORT QUESTION No.3-ii                                                                                       What are disadvantages of hard of water?

ANSWER:                                                                                             DISADVANTAGES of HARD of WATER:                                                                                                     (1) Drinking hard water cause stomach disorder.                                            (2)         Hard water consumes an excess amount of soap.         Moreover, it does not have good cleansing action.                                                               (3)           Using hard water in the boilers and turbines deposits salts inside them. It blocks the pipelines, which can cause boiler to explode.

SHORT QUESTION No.3-iii                                                                                 How permanent hardness of water is removed?

ANSWER:                                                                                                    When an appropriate amount of washing soda (sodium carbonate) is mixed with permanent hard water, chemical reaction takes place and soluble chlorides and sulphates of calcium and magnesium are converted into insoluble carbonates.                                                                                             In this way, permanent hardness of water is removed.

SHORT QUESTION No.3-iv                                                                         What are the methods used to kill micro organisms present in water?

ANSWER:                                                                                                                 (1)   Germs, bacteria and other micro organisms present in water may be killed by boiling it in a large container for 15 to 30 minutes.                                                                                                                  (2)           Water supplied for domestic purpose is usually mixed with liquid chlorine to kill germs.                                                                                                     (3)       Aeration of water in the presence of sunlight, heat and kills most of the germs present in it.


What is the disadvantage of water being universal solvent?

ANSWER:                                                                                                         Water being universal solvent, natural water has a number of impurities dissolved in it.                                                               Moreover, clay, sand and microorganisms like bacteria are also found in it.

LONG QUESTION No.5                                                                                What are the factors, which cause water pollution? Describe them in detail?

ANSWER:                                                                                                               The harmful compounds are called “_water pollutants” which cause water pollution.                                                                                                         (i) One of the main causes of water pollution is the use of fertilizers in agricultural land.
(ii) Similarly, animals and industrial wastes are thrown in canals, pounds, rivers and wells, this serves as the major cause of water pollution.                                                                                                                  (iii) The presence of mineral oil in seawater is another major source of water pollution.                                                                                        (iv) Sewage water discharged without treatment into streams, lakes, canals and rivers also causes water pollution.

QUESTION No.7                                                                                          How water logging and salinity are developed in the soil? Describe them in detail?

ANSWER:                                                                                                                  WATER LOGGING:                                                                                                        Rainwater, water used for irrigation and water present in canals, lakes, streams and rivers, which flow hundreds of kilometers, goes underground due to constant seepage. When, such water reaches impermeable rocks, its level starts rising. It is called “water table”. When this “water table” rises up to the earth’s surface, it is called “water logging”.                                                     WATER SALINITY:                                                                                  Water also contains soluble salts. When it is evaporated by solar heat, the salts are left behind on the surface of the earth. This process is called “soil salinity”.

LONG QUESTION No.8                                                                              Describe the methods used for the removal of water logging and salinity?

ANSWER:                                                                                                      WATER LOGGING REMOVAL METHODS:                                                 (1) By installation of tube-wells, the water level can be lowered.                                                                                                           (2) Drainage channels are dug in water- logged land that can drain off excess water to nearby canals or rivers.                                                    (3) Filter pipes made of mud, are buried underground through which surplus water can flow to drainage channels.                                                                                            WATER SALINITY REMOVAL METHODS:                                                           (i)     The land effected by salinity is irrigated using excess of water.                                                                                                                (ii) In case of over- irrigated land, those plants and crops are cultivated which require excess of water.                                                              (iii)         Chemical methods ma also be employed to remove salinity. Fertilizers like gypsum chemically react with these salts and convert them into such compounds which are
not harmful for crops.

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i- There is ————————————————-in between the double walls of thermos flask,

ii-Good absorbers are good—————————-

iii- Winds blowing from sea to coastal area are called——————————————————

iv) Land and sea breezes are caused due to difference of————————————————-

ANSWERS: (i-vacuum)(ii-emitters)(iii-sea breezes)                         (iv-pressure)



(i) How does heat pass through vacuum?

(a)          By conduction

(b)          By convection

(ii) Why is the water heating coil placed near bottom of kettle.

(b)          Hot water rises up.

(c)          By radiation

(a)    Water is a good conductor.

(c)    Water is good radiator.

(iii) From which surface does the heat radiate quickly?

(a)    From black surface.

(c)    From silver surface

(iv) Sun heats the doorknob. Which method of heat transfer contribute to heat the inside doorknob?

(a)          By conduction

(b)          By convection

(b)          From red surface

(c)          By radiation

ANSWERS: (i-c)(ii-b)(iii-a)(iv-a)





QUESTION No. (i)                                                                              Which material is used to make handles and knobs of objects in daily use and why?


QUESTION No. (ii)                                                                                                           What principle do ventilators and windows obey in a house?


QUESTION No. (iii)                                                                                     Why silver teapot is preferred to black tea pot?


QUESTION No. (iv)                                                                                     Make a sketch of thermos flask and label its parts.


QUESTION No. 4                                                                                             What do you mean by conduction? Describe by an experiment. Give examples of its application in daily life.

ANSWER:                                                                                                                                  The process of heat transmission from one part of solid body the next part by molecular vibration is called conduction.                                                               EXPERIMENT                                                                                                   Fix three thumb pins by wax at equal distances on one side of metal rod. Place it on wooden block. Now , heat the other end.                                                                           After some time wax of pin No.1 is melted and it drops, after that 2nd and then the last pin also falls down. Heat reaches slowly from one end of the rod to the other due to conduction.

QUESTION No. 5                                                                                     How will you explain experimentally, the process of convection? Give two examples of its application in daily life.

ANSWER: Water molecules transfer teat from one place it the other by their movement.                                                                                               EXPERIMENT:                                                                                             Take cool water in beaker. Put two or three crystals of pink colour at its bottom.                                                                                                          Now heat it by the side. Water expands after getting heat which deceases its density and it rises up. Cold water molecules from the sides take that place. Slowly cold water starts whirling until the whole water becomes coloured.


QUESTION No. 6                                                                                           What is meant by radiation? How will it be explained?

ANSWER:                                                                                                     The method of reaching heat from the sun or any other source by radiation is called process of radiation or simply radiation.

QUESTION No. 7                                                                                  How does thermos flask maintain the temperature of the object inside it?


QUESTION No. 8                                                                                         What causes land and sea breezes?

ANSWER:                                                                                   .             During the daty air is contact with land expands on heating being lighter rises up. Thus pressure over that place lowers. Sea , which is cooler than land , has high pressure at the surface.                                                     .           Therefore air blows from an area of high pressure to an area of a low pressure. Land breezes blow at night from coastal to sea area.                                                                                                .             At night seaside is hot as compared to land so air at sea surface expands and raises up which lowers the pressure of that area which causes the cold air to blow from coastal area to the sea.

QUESTION No.9                                                                                           How will you prove that good absorbers are good emitters too?



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