DELHI PUBLIC SCHOOL AGRA

(Under the aegis of The Delhi Public School Society, East of Kailash, New Delhi)

Sample Paper 2
Class X 2022-23
Science (086)
Answer-key
Time: 3 Hours Max. Marks: 80
General Instructions:
1. This question paper consists of 39 questions in 5 sections.
2. All questions are compulsory. However, an internal choice is provided in some questions. A student is expected to
attempt only one of these questions.
3. Section A consists of 20 Objective Type questions carrying 1 mark each.
4. Section B consists of 6 Very Short questions carrying 02 marks each. Answers to these questions should in the range of
30 to 50 words.
5. Section C consists of 7 Short Answer type questions carrying 03 marks each. Answers to these questions should in the
range of 50 to 80 words.
6. Section D consists of 3 Long Answer type questions carrying 05 marks each. Answer to these questions should be in the
range of 80 to 120 words.
7. Section E consists of 3 source-based/case-based units of assessment of 04 marks each with sub-parts.

SECTION-A
Select and write one most appropriate option out of the four options given for each of the questions 1 – 20.

1. When pH strip is dipped in each bottle, the colour shown by bottle A and B will be respectively:

(a) orange, blue

(b) blue, orange
(c) green, blue
(d) blue, green

2. Complete the following chemical reaction with correct option:

Pb(NO3)2 + 2KI _______ + 2KNO3
(a) PbI2
(b) PbNO3
(c) Pb(NO3)2
(d) PbIO3
3. The given diagram represents a reaction.

(a) Thermal decomposition

(b) Displacement
(c) Double displacement
(d) Combination

4. CuO + H2 Cu + H2O
Which of the following pair is correct regarding oxidation and reduction?

Oxidation Reduction
(a) CuO H2
(b) H2 CuO
(c) H2O H2
(d) H2 H2O

5. Ionic compound have high melting point due to

(a) Strong force of attraction between oppositely charged ions.
(b) Less force of attraction between oppositely charged ions.
(c) Strong force of attraction between similar charged ions.
(d) None of these

6. Which of the following substances will not give carbon dioxide on treatment with dilute acid?
(a) Marble
(b) Limestone
(c) Baking soda
(d) Lime

7. Which of the following are correct structural isomers of butane ?

 (a) (i) and (iii)
(b) (i) and (ii)
(c) (ii) and (iv)
(d) (iii) and (iv)

8. The diagram shows part of the human gas exchange system.

Here, W, X,Y and Z are?

Bronchus Bronchiole Larynx Trachea

(a) W X Z Y
(b) X Z Y W
(c) Y W X Z
(d) Z Y W X
9. Which process is shown by the following picture?

(a) Movement of food during photosynthesis in a tree

(b) Movement of water during transpiration in a tree
(c) Movement of minerals during in a tree
(d) Movement of carbon dioxide during in a tree

10. Each gamete carries only one allele. This is proposed in which law ?
(a) law of dominance
(b) law of segregation
(c) law of genetics
(d) law of assortment

11. Which of the following statements about transmission of nerve impulse is incorrect ?
(a) Nerve impulse travels from dendritic end towards axonal end.
(b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical
impulse at the axonal end of another neuron.
(c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical
impulse in a dendrite of another neuron.
(d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells.

12.The reproductive life of a woman lasts from

(e) reproductive life a woman lasts from menarche to menopause.
(f) reproductive life a woman lasts from menarche to menstruation
(g) reproductive life a woman lasts from chenmare to pausemeno.
(h) reproductive life a woman lasts from chenmare to usemenopa.

12. Electrical resistivity of a given metallic wire depends upon

(a) its length
(b) its thickness
(c) its shape
(d) nature of the material
 Sample Paper 2 Page 5

13. Choose the incorrect statements from the following regarding magnetic lines of field.
(a) the direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass
needle points
(b) magnetic field lines are closed curves
(c) if magnetic field lines are parallel and equidistant, they represent zero field strength
(d) relative strength of magnetic field is shown by the degree of closeness of the field lines
s

14. The proper representation of series combination of cells (Figure) obtaining maximum potential is

(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)

15. Which of the following factors affect the strength of force experience by a current carrying conductor in a uniform
magnetic field?
(a) magnetic field strength
(b) magnitude of current in a conductor
(c) length of the conductor within magnetic field
(d) All of above.

Question no. 17 to 20 are Assertion - Reasoning based questions.

16. Assertion : When iron nail is dipped in copper sulphate solution, the iron nail becomes brownish in colour and the blue
colour of copper solution fade.
Reason : Equation representing this change is
Cu + FeSO4 CuSO4 + Fe
(a) Both Assertion and Reason are True and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are True but Reason is not the Correct explanation of the Assertion.
(c) Assertion is True but the Reason is False.
(d) Both Assertion and Reason are False.
17. Assertion : Chromosomes are known as hereditary vehicles.
Reason : The chromosomes are capable of self-reproduction and maintaining morphological and physiological properties
through successive generations.
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.

18. Assertion : Ethanol is obtained during the anaerobic process of respiration.

Reason : This is due to presence of oxygen and it takes place in the mitochondria.
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Both Assertion and Reason are false.

19. Assertion : A current carrying conductor experiences a force in a magnetic field.

Reason : The force acting on a current carrying conductor in a magnetic field is due to interaction between magnetic field
produced by the current carrying conductor and external magnetic field in which the conductor is placed.
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.

SECTION-B
Question no. 21 to 26 are very short answer questions.

20. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it as
shown in Figure below :
(a) What will be the action of gas on
(i) dry litmus paper ?
(ii) moist litmus paper ?
 OR
Write some uses of metals which are based on the properties of malleability and ductility.
Ans-a. (i)-No change in colour
(ii) Litmus paper will become red due to the formation of sulphurous acid .
OR
Malleability means that metals can be hammered into sheets and foils. For example, aluminum foils are used for wrapping food stuffs, silver
foils are used for decorative purposes on sweets and fruits. Ductility means that metals can be drawn into wires. Gold and silver wires are used
in ornaments.
21. (a) What will happen to the guard cells and stomatal pore when water flows to guard cells ?
(b) How do plants transmit informations from cell to cell ?
ANS: (a) Guard cells regulate the opening and closing of stomatal holes, which are controlled by the process called
osmosis. The entry of water into the stomata makes guard cells swell which leads to the opening of the stomata.
The stomata close when the guard cells lose water and constrict, becoming flaccid and straight.
(b) lant cells communicate with each other via narrow channels embedded across adjacent cell walls. These
channels, called plasmodesmata, allow molecules to pass between cells, thereby enabling plants to grow normally
and develop tissues and organs.

22. What is the compensation point with relation to the release of CO2 by the plants ?
ANS: The compensation points is where the photosynthetic rate becomes zero. In assimilation terms, at the
compensation point, the net carbon dioxide assimilation is zero. Leaves release CO2 by photorespiration and cellular
respiration, but CO2 is also converted into carbohydrate by photosynthesis.

23. What is the cause of peptic ulcer ?

ANS: The most common causes of peptic ulcers are infection with the bacterium Helicobacter pylori (H.
pylori) and long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil,
Motrin IB, others) and naproxen sodium (Aleve). 

24. A person is not able to see distinctly the objects placed beyond 90 cm from him. Giving reasons to identify the defect in his
eye. Determine the nature of lens used to correct this defect.
OR
What do you mean by scattering of light?Give an example .
ANS Person is suffering from hypermetropia ,as he couldn't see the nearer object clearly and can see the distant object
clearly .
REASON:1. the hypermetropic eye has low converging power .2.has smaller eye ball

CORRECTION:It can be corrected using convex lens

OR

Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle

like dust or gas molecules, water vapours etc. Scattering of light gives rise to many spectacular phenomena such as

Tyndall effect and the “red hues of sunrise and sunset”. The colors we see in the sky are due to scattering of light.

25. “Energy flow in a food chain is unidirectional.” Justify this statement.

ANS: •Sun is the only source of energy. Producers convert solar energy into chemical energy in
the form of food.
•The primary consumers (herbivores) depends on producers for food.
•According to the energy transfer law, only 10% of energy is transferred from one trophic level
to the other.
•Therefore, the energy that is captured by the producers does not come back to the Sun and
the energy transferred to the herbivores does not come back to the producers.
•It just keeps on moving to the next trophic level in a unidirectional way.
•That is why the flow of energy in the food chain is always unidirectional.

SECTION-C
Question no. 27 to 33 are short answer questions.

26. Identify the type of each of the following reactions stating reason for your answers :
(a) Fe2 O3 + 2Al → Al2 O3 + 2Fe + heat
(b) Pb(NO3)2 + 2Kl→ Pbl2 + 2KNO3
(c) ZnCO3 ZnO+CO2
Ans-(a)-Displacement reaction,Al is more reactive than Fe
(b)Double displacement reaction,ions are exchange
(c) Thermal decomposition reaction ,decomposition occurs in presence of heat.
27. Explain the following statements :
(a) Most metal oxides are insoluble in water but some of these dissolve in water. What are these oxides and their
solutions in water called ?
(b) At ordinary temperature the surface of metals such as magnesium, aluminium, zinc etc., is covered with a thin layer.
What is the composition of this layer ? State its importance.
(c) Some alkali metals can be cut with a knife.
Ans-a.-Those metal oxides which are soluble in water are called basic oxides and their
solutions in water are called alkalis.Na2O +H2O→NaOH
b-At ordinary temperature, the surfaces of metals such as magnesium, aluminium, zinc, lead,
etc., are covered with a thin layer of oxide. The protective oxide layer prevents the metal
from further oxidation.
c .Alkali metals (Li, Na, K) are so soft that they can be cut with a sharp knife. This is possible
because of the weak forces of attraction between the atoms.

28. Study the picture carefully and answer the following:

I
 (a) What does diagram given below depict?
(b) What are A and B ?
(c) Which vessel carried deoxygenated blood to lungs and which vessel brings oxygenated blood from lungs to heart ?
OR
How does small intestine tissues help the digestion of fats, protein and starch?
ANS:(a)Schematic diagram of blood circulation
(b)A: Pulmonary circuit B: Systemic circuit
(c)The pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs.
The pulmonary veins carry oxygenated blood from the lungs to the left atrium.

OR
Digestion of carbohydrates: Digestion of carbohydrates begins from buccal cavity. Salivary
amylase converts starch into sugar. Other complex carbohydrates are convened into glucose in
the small intestine.
Digestion of Proteins: Protein is partially digested in the stomach. For this, stomach
secretes the enzyme pepsin. In small intestine, pancreatic juice provides the enzymes trypsin
and chymotrypsin. These enzymes complete the digestion of proteins.
Digestion of Fats: Digestion of fats takes place in small intestine. Bile; from liven emulsifies
the fat. Due to this, fat is broken into small globules. This makes it easier for the enzyme to
digest fat. Lipase is the enzyme which converts fat into glycerol and fatty acid.

30(a) State the relationship between focal length and radius of curvature of a spherical mirror.
(b) Why is the refractive index of a medium always greater than one ?
(c) A lens has -4 D power. Is the lens concave or convex ?
ANS (a) R=2f
(b) Because the speed of light in any medium is always less than that in a vacuum.
(c ) Concave lens

31. (a) Define power of a lens and write its S.I. unit.
(b) A convex lens of power 4 D is placed at a distance of 40 cm from a wall. At what distance from the lens should a
candle be placed so that its image is formed on the wall ?
ANS.(a) Power is defined as the reciprocal of focal length.Its S.I unit id Dioptre (D).
(b) f=1/P =25 cm.
now 1/u=1/v -1/f =-3/200 cm or u= -200/3 cm

32.A shining metal M , of burning gives a dazzling white flame and changes to a white powder N .
(d) Identify M and N .
(e) Represent the above reaction in the form of a balanced chemical equation.
(f) Does M undergo oxidation or reduction in this reaction ? Justify.
OR
Write the equations for the following metals which are obtained from their compounds by reduction process.
(a) Metal X which is low in reactivity series.
(b) Metal Y which is in the middle of the series.
Ans-(a) -Magnesium metal and magnesium oxide
(b) -2Mg+O2 →2 MgO
 ( c)-M undergo oxidation reaction, as oxygen is added to M
OR
Ans-(a)-(i) Metal X is obtained simply by heating their oxides. e.g., mercury is obtained
from cinnabar.

(ii)Metals Y in the middle of activity series can be obtained by heating with carbon, e.g.,

Larger animals kill the smaller animals in the forest, eat whatever they can, leave the rest in the forest but the forest is never
found full of dead animals. What happens to the bodies of these dead animals?

SECTION-D
Question no. 34 to 36 are Long answer questions.

29. Soaps and detergents are both types of salts. State the difference between the two. Write the mechanism of the cleaning
action of soap. Why do soaps not form lather with hard water ? Mention any two problems that arise due to the use of
detergents instead of soaps.
OR

Ans- 1. Soaps are the sodium and potassium salts of long chain carboxylic acids whereas detergents are
ammonium or sulphonate salts.
2. Most of the dirt is oily in nature and oil does not dissolve in water. The molecule of soap constitutes sodium or potassium salts of
long-chain carboxylic acids. In the case of soaps, the carbon chain dissolves in oil and the ionic end dissolves in water. Thus the soap
molecules form structures called micelles. In micelles, one end is towards the oil droplet and the other end which is the ionic faces
outside. Therefore, it forms an emulsion in water and helps in dissolving the dirt when we wash our clothes.

3. When soap is mixed with hard water, the calcium and magnesium salts displaces the salts of sodium and potassium present in the
soap and forms scum which is not soluble. Hence soaps are not effective in hard water for washing clothes.

4. Demerits: a. Detergents are non-biodegradable.

b. Detergents are harsh on skin as compared to soap.

OR
30. (a) Differentiate between germination and fertilization.
(b) State in brief the functions of the following parts of the human male reproductive system :
(i) Scrotum
(ii) Testes
(iii) Vas deferens
ANS: (a) Germination is the process by which a dormant seed which contains the , begins to sprout and
grow into a seedling under the right growing conditions. Whereas The union of male gamete (sperm) with
the female gamete (ovum) to form a diploid zygote is called fertilisation.
(b).(i) The scrotum protects your testes, as well as providing a sort of climate control system. (ii)
Testes : It produces sperms and male sex hormone- testosterone. (iii) Vas Deferens : It helps in the
passage of sperms
OR
(a) Draw a neat diagram to show fertilization in a flower and label on it the following parts :
(i) Stigma
(ii) Pollen tube
(iii) Ovary
State the function of pollen tube.
(b) List in tabular form any two differences between a male gamete and a female gamete.
ANS: (a)

The pollen tube (PT) is a unique and specialized structure in plants. Its sole purpose is to deliver
sperm cells to the female gametophyte for double fertilization.
(b)

.no Male Gametes Female Gametes

.

1. The male gametes are known as sperms and are The female gametes are known as the
produced by the process of spermatogenesis. egg or ovum and are produced by
oogenesis.

2. They are usually small and motile. They are large and nonmotile.

3. They are produced in large numbers. Only a single gamete is formed at a time.

4. In humans, the male gametes decide the Female gametes do not determine
sexuality of the offspring. sexuality in humans.

31. (a) For the combination of resistors shown in the following figure, find the equivalent resistance between M and
N.
 (b) State Joule’s law of heating.
(c) Why we need a 5 A fuse for an electric iron which consumes 1 kW power at 220 V?
(d) Why is it impracticable to connect an electric bulb and an electric heater in series?

ANS (a) R=R1+R2+ R3X R4/R3+R4

(b) Joule's Law of Heating - The heat produced in a resistor is directly proportional to
1. Square of current for a given resistance
2. The resistance for a given current and
3. The time for which the current flows through the resistor
(c) P = V I or I = P/ V I = 1000 watt/ 220 volt = 4.54 A ,Since 4.54 ampere current flows in the circuit , a 5 A fuse
must be used.
(d) It is impracticable to connect an electric bulb and an electric heater in series because Electric bulb & electric
heater will not get currents and voltages as per their requirement.

SECTION-E
Question no. 37 to 39 are case-based/data -based questions with 2 to 3 short sub-parts. Internal choice is provided in one of
these sub-parts.

32. Sample of four metals P, Q, R and S were taken and added to the following solution one by one. The results obtained have
been tabulated as follows.

Metal FeSO4 CuSO4 ZnSO4 AgNO3

P No reaction Displacement .......... ..........
Q Displacement No reaction Displacement
R No reaction No reaction No reaction
S No reaction No reaction No reaction No reaction
(i) Which is the most reactive metal ?
(ii) What would you observe if Q is added to a solution of CuSO4 . Also, what is the colour change when Q is added to
FeSO4 .
OR
What do you mean by displacement reaction ?
Ans-(i) Q is most reactive
(ii) If Q is added to CuSO4
4 solution than it will displace Cu because Fe is more reactive than Cu so the metal which can displace Fe can also displace Cu.
OR
The reaction in which more reactive metal displaces the less reactive metal from its compound, is called as displacement reaction.
Zn+CuSO4→ZnSO4+Cu.
 33. Question numbers i - iv are based on the table given below. Study the table and answer the following questions.
Table-A

S. No. Generation Phenotypic ratio

1. F1 generation 23 pairs

2. F2 generation 22 pairs

(i) State the law of dominance.

(ii) What is the dominant allele?
(iii) Define the term phenotype.
oo
(iv) What is the meaning of genotype ?
ANS: (i)
Law of Dominance:

1. Law of dominance is known as the first law of inheritance.

2. Each character is controlled by distinct units called factors, which occur in pairs.

3. If both the factors are present in the organism, one act as dominant over the other.

Explanation:

1. Law of dominance explains that in a monohybrid cross between a pair of contrasting traits, only one

parental character will be expressed in F1 generation and both are expressed in F2 generation in the

ratio 3:1.

2. The one which expressed in F1 generation is called dominant trait and the one which is suppressed

is called recessive trait.

3. In simple words, the law of dominance states that recessive traits are always dominated or masked

by dominant trait.​

4. For example, when pea plants with round seeds (RR) are crossed with plants with wrinkled seeds

(rr), all seeds in F1 generation were found to be round (Rr).

5. When these round seeds were self fertilized, both the round and wrinkled seeds appeared in F2

generation in 3: 1 ratio.

6. Hence, in F1 generation, the dominant character (round seeds) appeared and the recessive

character (wrinkled seeds) got suppressed, which reappeared in F2 generation.

(ii) In heterozygous condition, the allele which expresses itself even in the presence of another
allele is called a dominant allele. The allele whose expression is suppressed in the presence of a
dominant allele is called a recessive allele.
 (iii)Phenotype refers to an individual's observable traits, such as height, eye color and blood
type. A person's phenotype is determined by both their genomic makeup (genotype) and
environmental factors.
OR
(iv) A genotype is a scoring of the type of variant present at a given location (i.e., a locus) in
the genome. It can be represented by symbols. For example, BB, Bb, bb could be used to
represent a given variant in a gene.
34. A concave mirror forms image of an object thrice in its size on a screen. Magnification of a mirror gives information about
the size of the image relative to the object. It is defined as the ratio of size of image to the size of object. It is represented by
m.

m = Size of image
Size of object
Sign of magnification by mirror gives the information about the nature of the image produce by it.
(i) Describe the nature of image formed.
(ii) If the object x distance from the pole of mirror, then find image distance from the pole.
(iii) If the radius of curvature of mirror is R, then write the relation between object distance, image distance and focal
length of the mirror.
oo
(iv) Give one use of concave mirror.
ANS (i) real ,inverted & enlarged
(ii) v = -3x as m = - v/u
(iii) 2/R =1/v +1/f

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