CBSE

Class 10 Science
Sample Paper 01

General Instructions:

1. The question paper comprises two sections, A and B. You are to attempt both the sections.
2. All questions are compulsory.
3. All questions of Section-A and B are to be attempted separately.
4. There is an internal choice in 2 questions of 3 marks each and 1 question of 6 marks.
5. Question numbers 1 and 2 in Section-A are one mark question. They are to be answered
in one word or in one sentence.
6. Question numbers 3 to 5 in Section- A are two marks questions. These are to be answered
in 30 words each.
7. Question numbers 6 to 15 in Section-A are three marks questions. These are to be
answered in about 50 words each.
8. Question numbers 16 to 21 in Section-A are 5 marks questions. These are to be answered
in 70 words each.
9. Question numbers 22 to 27 in Section- B are based on practical skills. Each question is a
two marks question. These are to be answered in brief

Section A

1. How may male gametes are produced by pollen grains?

2. Name the largest artery in the human body.

3. By considering their position in the Periodic Table, which one of the following
elements would you expect to have maximum metallic characteristic?
Ga, Ge, As, Se, Be

4. Light is incident at an angle of

(i)
(ii) , on the same face of a given rectangular slab. If the angles of refraction, at
this face are and in the two cases. Obtain the relation in these angles?

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 5. State the important uses of solar cells.

6. (a) An aqueous solution has a PH value of 7.0. Is it acidic, basic or neutral?

(b) If H+ concentration of a solution is mol L-1 what will be its P4 value?

(c) Which has higher PH value: 1 - M HCl or 1 - M NaOH

OR

Draw ray diagram showing the image formation by a concave mirror when an
object placed at centre of curvature of the mirror.

7. What are the advantages of connecting electrical devices in parallel with the battery
instead of connecting them in series?

8. How can three resistors of resistance 2 , 3 and 6 be connected to give a total

resistance of (i) 4 , (ii) 1 ?

9. Write two major shortcomings of Mendeleev's periodic table? How have these been
removed in the modern periodic table?

10. Describe double circulation in human beings. Why is it necessary?

OR

Draw ray diagram showing the image formation by a convex lens when an object is
placed at infinity.

11. Outline a project which aims to find the dominant coat colour in dogs.

12. A change in DNA that is useful for one property to start with, can become useful
later for a different function. Explain.

13. Why is respiration considered as an exothermic reaction? Explain.

OR

Draw ray diagram showing the image formation by a convex lens when an object is
placed at twice the focal length of the lens.

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14. A truck uses a convex mirror as view finder whose radius of curvature is 2.0 m. A
maruti car is coming behind the truck at a distance of 10 m. What will be the
position of the image of the car and size of the image of the car when observed by
the driver of the truck through the convex mirror?

15. What are the major factors responsible for population explosion?

16. Explain the underlying principle and working of an electric generator by drawing a
labelled diagram. What is the function of brushes?

17. (a) Why does carbon form large number of compounds?

(b) Why are some of these called saturated and others are called unsaturated
compounds?
(c) Which of these two is more reactive?
(d) Write the names of the following compounds:

OR

Draw ray diagram showing the image formation by a convex lens when an object is
placed between optical centre and focus of the lens.

18. How phototropism does occur in plants?

19. (a) What is myopia? State the two causes of myopia. With the help of labelled ray
diagrams show
(i) the eye defect myopia
(ii) correction of myopia using a lens.
(b) Why is the normal eye can't focus on an object placed within 10cm from eye?

20. An ore on treatment with dilute hydrochloric acid gives a smell like that of rotten
eggs. What type of ore is this? How can it be concentrated? How can the metal be
obtained from the concentrated ore?

21. Describe how ozone layer is formed.

OR

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 Draw ray diagram showing the image formation by a concave lens when an object is
placed beyond twice the focal length of the lens.

Section B

22. Salt A commonly used in bakery products on heating gets converted into another
salt B which itself is used for removal of hardness of water and a gas C is evolved.
The gas C when passed through lime water, turns it milky. identify A, B and C.

23. The observation in I and II will be:

24. In tobacco plant, the male gametes have twenty four chromosomes. What is the
number of chromosomes in the female gamete? What is the number of
chromosomes in the zygote?

25. Can you, design any other experiment set-up for testing that CO2 is produced during

respiration?

26. Draw ray diagram showing the image formation by a convex lens when an object is
placed at the focus of the lens.

OR

Draw a ray diagram showing the path of rays of light when it enters with oblique
incidence (i) from air into water, (ii) from water into air.

27. A Child has drawn the electric circuit to study Ohm's law as shown in Figure.

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 CBSE Class 10 Science
Sample Paper 01
Solution

Section A

1. Two,One fuses with ovum and another fuses with other cell in ovule which
nourishes the zygote formed

2. Aorta is the largest artery in the human body..

3. Metallic character of an element increases down a group and decreases from left to
right in period. On this basis Be is expected to have maximum metallic character.

4.

5. Important uses of solar cells are as follows..

(i) for providing electricity in artificial satellites.
(ii) for lighting the street lights, traffic signals, running television sets and radio sets
in remote areas.
(iii) for providing electricity in lighthouses.
(iv) for operating electronic watches and calculators.

6. (a) The solution is neutral is nature.

(b) [H+] =

= 10-2M

PH =

= - log [H+]

= - log [10-2]
= -(-2)log 10 = 2

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 (c) 1 M NaOH solution (basic) higher PH. Value
1 M HCl solution (acidic) lower PH. Value

OR

7. Advantages of connecting electrical devices in parallel with the battery are as

follows:
(i) The voltage across each connecting electrical device is same and the device
consumes current as per its resistance.
(ii) Separate on/off switches can be applied across each device.
(iii) Total resistance in parallel circuit decreases, hence, a great current may be
drawn from the cell.
(iv) If one electrical device is damaged; then other devices continue to work
properly. Moreover,total resistance in parallel circuit arrangement
decreases.Hence,there is less heat dissipated as compared to series connection.

8. (i) As the total resistance (equivalent resistance) is 4 , the 6 resistor cannot be in

series as in series combination the equivalent resistance is greater than the largest
individual resistance. So, it must be in parallel with the other resistors.
In parallel connection, the equivalent resistance (4 ) has to be less than all the
resistances.
So, the resistors of 2 and 3 cannot be in parallel at one time with 6 So, the
resistors have to be in a mixed combination. Let us consider the combination shown
in the figure.

The equivalent resistance between B and C (which are in parallel).

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 =
=
The resistance between A and D = 2 +2 =4 .
So, the combination shown in the figure is true.
(ii) Here, R1 =2 , R2 =3 , R3 =6 , and R= 1

Since the equivalent resistance of the combination is of lesser value than any of the
resistors of the combination, it is clear that the resistors should be connected in
parallel. It can be further confirmed by using the formula

=
=
= 1 , i.e, R=1
Therefore, resistors should be connected in parallel.

9. The two major short comings of Mendeleev’s periodic table were

(i) It could not justify the position of hydrogen in the periodic table whether in
group 1 or group 8
(ii) It could not assign proper position to the different isotopes of the same element.
The main reason for these short comings was the basis of the Mendeleev’s periodic
table. It regarded atomic masses of the elements as the basis of classification. The
modern periodic table regards atomic numbers of the elements as the basis of
classifying the elements. It removed both the short comings from the table.

10. In mammals and birds the blood goes through the heart twice during each cardiac
cycle. This is known as double circulation.
Deoxygenated blood which enters right auricle and then it enters the right ventricle
from where it is pumped to lungs for oxygenation. From lungs after oxygenation it
comes to left auricle and then enters left ventricle from where it is pumped to
various parts of body.
Such system of circulation does not allow mixing of oxygenated and deoxygenated

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 blood which allows efficient supply of oxygen to the body.

OR

11.

i. Select two varieties of dogs one with white coat colour, the other with black
coat colour.

ii. Crossbreed them taking male dog from one variety and bitch (female dog) from
the other variety.

iii. Observe the colour of offsprings of F1 generation.

iv. Now, bring about breeding among the organisms of F1 generation.

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 v. Observe the coat colour of organisms (pups) of F2 generation and note the
variations in coat colour.

vi. Draw conclusions on the basis of your study. One of the probable inheritance
pattern may be as given below. Phenotypic ratio = 3 : 1, Black coat colour (3) :
White coat colour (1)

12. A change/feature/property of an organism that may have helped it to adapt to an

environmental condition can also become useful for a completely different function
in the future. For example: feathers in birds, a character developed and selected
during natural selection because it provided insulation in cold weather have
become useful in later stages for flight. Some dinosaurs had feathers, but they could
not fly. Birds later adapted the feathers to flight.

13. Rice, potatoes and bread contain carbohydrates. During digestion, these
carbohydrates are broken down into simpler substances called glucose. Digestion
follows respiration. During respiration, the glucose combines with oxygen in the
cells of our body and provides energy. Thus, respiration is an exothermic process
because energy is produced during this process.

OR

14. For convex mirror, we have given, u = - 10 m, R =2.0 m

So, f = =
Using the mirror formula,

We get,

or, v = = 0.9 m

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 Thus, the car would appear at 0.9 m from the convex mirror. We know that

m = =
Thus, size of the image of the car will be a fraction of the actual size of the car
through the convex mirror.

15. Reason for population explosion-

i. Better medical facilities- Better medical facilities have resulted in fall of death
rate.

ii. Lack of education and awareness- This is a major factor since people become
prey to ignorance

iii. Religion- For some people, family planning is against the norms set by their
religion.

iv. Control over epidemics- Various medical technologies has made it possible to
fight against epidemics.

v. Sanitary conditions- There is a lot of improvement in sanitary conditions

which led to increase in population.

16. Electric generator labelled diagram is as follows:

Principle: An electric generator works on the principle of electromagnetic

induction.
Working: Let the in the beginnings brushes B1 and B2 are kept pressed separately

on rings R1 and R2 respectively. Let the axle attached to the rings is rotated such that

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 arm AB of the coil moves up and arm CD moves down in the magnetic field. Due to
rotation of arms AB and CD induced current are set up in them. As per Fleming’s
right hand rule, induced current in these arms along the directions AB and CD
respectively and current flows into B1 and B2.

After half rotation, arm AB moves downward and arms CD upward to change the
direction opposite to first case. Thus, after every half rotation current changes its
direction and an alternate current is obtained in the generator.
Brushes are kept pressed on the two slip rings separately. Outer ends of the brushes
are connected to the galvanometer. Thus, brushes help in transferring current from
the coil ABCD to external circuit.

17. (a) Carbon forms a large number of compounds called organic compounds due to
the self linking property called catenation. Carbon can combine with other carbon
atoms and form long chains. The long chain forms the backbone to which other
atoms can attach in a number of ways. Tetravalent carbon is capable of bonding
with four other atoms of carbon or some other mono-valent element(s). The bond
formed by carbon is exceptionally strong due to its small size.
(b) Compounds which have only (single bond) are saturated
compounds whereas those compounds which have bonds (double
bonds) or bonds (triple bonds) are called unsaturated compounds.
(c) Unsaturated compounds are more reactive than saturated compounds. E.g.
ethene is more reactive than ethane .
(d) (i) isBromoethane
(ii) is Hex-1-yne

OR

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18. The directional movement of a plant part/plant in response to light is called
phototropism. The shoot responds by bending towards light while roots respond by
bending away from the light. We know that the plant stem responds to light and
bends towards it due to the action of auxin hormone. When sunlight comes from
above, then the auxin hormone present at the tip of the stem spreads uniformly
down the stem. Due to the equal presence of auxin, both the sides of the stem grow
straight and with same rapidity.This is because auxin hormone moves away from
the light.
Thus, more auxin hormone is present in the left side of stem as compared to the
right. The left side of stem, grows faster than its right side and therefore, the stem
bends towards the right side (direction of light).

The effect of auxin on the growth of a root is exactly opposite to that on a stem.
Auxin hormone increases the rate of growth in stem but it decreases the rate of
growth in a root. The side of root away from light will have all the auxin
concentrated in it. Due to this, the side of root which is away from light will grow
slower than the other side and make the root bends away from light.

19. (a) Myopia is the defect of the eye vision due to which a person can see the near by
objects clearly but cannot see the far objects so distinctly.
Causes of myopia: Myopia is caused due to:
(i) the elongation of the eyeball.
(ii) decrease in the focal length of the eye lens.

(i)

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 (ii)

Myopia can be corrected by using a concave lens of suitable focal length in the
spectacles of such a person.
(b) The ability of the eye lens to adjust its focal length is called power of
accommodation. However, the focal length of the eye lens cannot be decreased
below a certain limit. The maximum accommodation of a normal eye is reached
when the object is at a distance of 25 cm from the eyes. Thus, the normal eye is
unable to focus an object placed within 10 cm from the eye because the nearest
distance of distinct vison for a normal eye is 25cm.

20. The gas which smells like that of rotten eggs is . Hence, the ore is a sulphide
ore. It is concentrated by froth-floatation process. The metal is obtained from the
concentrated ore in the following two steps:
(i) Roasting: Heating the ore strongly in the presence of air. The metal sulphide is
converted into metal oxide along with evolution of sulphur dioxide gas.

(ii) Reduction with carbon: On heating the metal oxide with carbon, it is reduced to
free metal.

21. Formation of the ozone layer-

(a) During the origin of life Earth, some of underwater photosynthetic micro-
organisms released molecular oxygen O2 in air as a by product of photosynthesis .

(b) This oxygen is released to stratosphere where it began to react with ultraviolet
radiations from sun to form free oxygen (O).

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 (c) Free oxygen combines with molecular oxygen to form in presence of
U.V. light.

Formation of ozone.

OR

Section B

22. Salt A is sodium hydrogen carbonate (baking soda). When it is heated, it turns into
sodium carbonate; which is salt B. In this reaction, carbon dioxide gas is also
produced; which is the gas C.

Sodium hydrogen carbonate is used in bakery products. Sodium carbonate is used

for removing hardness of water.

23. The solution becomes colourless in I and grayish coloured iron metal gets deposited,
in II, blue colour changes to pale green and reddish brown copper metal gets
deposited.

Al is more reactive than Fe.

Fe is more reactive than Cu.

24. Number of chromosomes in both the gametes is equal. Hence, female gametes of
tobacco plant will have 24 chromosomes. Number of chromosomes in zygote would
double the number in gametes, hence it would be 48.

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25. Yes, an experiment set-up by using two-head bottle, water reservior, germinating
seed, lime water, beaker and delivery tube.

26.

OR

The following figure shows a ray of light incident obliquely. Every medium has a
critical angle. When angle of incidence is more than critical angle, the ray of light
comes back in the same medium. This phenomenon is called total internal
reflection.

27. Correct diagram is as follows:

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