Class X - Science Sample Paper - 1 - Practice for Everyone

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General Instructions:

i. This question paper consists of 39 questions in 5 sections.

ii. All questions are compulsory. However, an internal choice is provided in some questions. A student is expected to attempt only one of these questions.

iii. Section A consists of 20 objective type questions carrying 1 mark each.

iv. Section B consists of 6 Very Short questions carrying 02 marks each. Answers to these questions should be in the range of 30 to 50 words.

v. Section C consists of 7 Short Answer type questions carrying 03 marks each. Answers to these questions should be in the range of 50 to 80 words.

vi. 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.

vii. Section E consists of 3 source-based/case-based units of assessment of 04 marks each with sub-parts.

Section A

Select and write the most appropriate option out of the four options given for each of the questions 1 – 20. There is no negative mark for incorrect response.

1. A single displacement reaction is represented below.

PQ + R —-> PR + Q

Which of the following is true about the reactants and products?

a) A b) B c) C d) D

View Answer

Ans. c) C

2. Some types of chemical reactions are listed below.

– decomposition

– combination

– displacement

– double displacement

Which two of the following chemical reactions are of the SAME type?

P) AgNO₃ + NaCl —> AgCl + NaNO₃

Q) Mg + 2 HCl —> MgCl₂ + H₂

R) CH₄ + 2 O₂ —> CO₂ + 2 H₂O

S) 2 KOH + H₂SO₄—> K₂SO₄ + H₂O

(a) P and Q (b) Q and R (c) R and S (d) P and S

View Answer

Ans. (d) P and S

3. Neetu has two test tubes containing dilute hydrochloric acid and dilute sodium hydroxide solution, but they are not labeled.

Adding which of the following solutions to the test tubes will help her to identify the acidic and basic solution?

– vinegar

– baking soda

– sodium chloride

(a) vinegar (b) baking soda (c) sodium chloride (d) (none of them)

View Answer

Ans. (b) baking soda

4. Sonia has aqueous solutions of three salts, sodium acetate, sodium chloride and ammonium chloride in three test tubes. The test tubes are not labeled. On checking, she finds the pH of the solutions to be 4.6, 7.0 and 8.9. Which of the following correctly matches the salts with their respective pH?

a) P b) Q c) R d) S

View Answer

Ans. d) S

5. Galvanisation is a process of coating iron articles with a layer of zinc to prevent the iron from rusting.

The iron is protected even if the zinc coating is scratched and iron is exposed.

Which of the following is true about how zinc prevents the rusting of iron?

P) A galvanised iron article does not undergo oxidation.

Q) The zinc coating prevents contact of iron with air.

R) Zinc undergoes corrosion more easily than iron.

(a) only P (b) only Q (c) only P and Q (d) only Q and R

View Answer

Ans. (d) only Q and R

6. During purification of a metal by electrolysis, what happens at the negative electrode?

(a) Metal ions lose electrons to become neutral atoms.

(b) Neutral metal atoms gain electrons to become ions.

(d) Metal ions gain electrons to become neutral metal atoms

View Answer

Ans. (d) Metal ions gain electrons to become neutral metal atoms

7. Metals are lustrous and shine especially when their freshly cut surfaces are exposed.

Salma cut pieces and compared the lustre of the freshly cut surfaces of the following metals.

aluminium, sodium, copper, iron

The freshly cut surface of which of these metals is likely to lose its lustre first on exposure to air?

(a) aluminium (b) sodium (c) copper (d) iron

View Answer

Ans. (b) sodium

8. Which of the following statements is TRUE about the uptake of water in plants?

(a) It occurs all the time due to diffusion.

(b) Water enters the roots due to osmosis.

(d) The movement of water from roots to leaves is bidirectional

View Answer

Ans. (b) Water enters the roots due to osmosis.

9. Oxygen saturation levels refer to the extent haemoglobin is bound to oxygen. As altitude increases, the atmospheric pressure decreases.

Which of the following graphs correctly represents the oxygen saturation levels as altitude increases?

(a) P (b) Q (c) R (d) S

View Answer

Ans. (b) Q

10. Which of the following method/s are useful to prevent fertilisation even when ovulation occurs?

P) surgical blocking of the fallopian tube

Q) copper-T

R) oral pills

S) condom

(a) only P (b) only Q and R (c) only P, Q and S (d) only Q, R and S

View Answer

Ans. (c) only P, Q and S

11. In cattle, having horns is a recessive trait (h) to not having horns (H). When cattle with horns are crossed with cattle that do not have horns, the number of offspring having horns was equal to those not having horns.

Which of the following is MOST LIKELY to be true?

(a) Both parents are homozygous dominant.

(b) One parent is homozygous dominant.

(d) One parent is heterozygous.

View Answer

Ans. (d) One parent is heterozygous.

12. Patient X was suffering from a pancreatic condition due to which the pancreas was not functioning adequately.

Which of the following is a doctor likely to suggest to such an individual?

(a) including a large amount of protein in the diet

(b) eating a diet with low-fat content

(d) including only liquid foods

View Answer

Ans. (b) eating a diet with low-fat content

13. When an object was kept at position X in front of a concave mirror, an enlarged and virtual image was formed.

Which among the following identifies ‘X’ correctly?

(a) anywhere between the centre of curvature and principal focus

(b) anywhere between the pole and principal focus

(d) exactly at the principal focus

View Answer

Ans. (b) anywhere between the pole and principal focus

14. The face of the moon that is visible to us is called as the near side and the face of the moon which is invisible to us is called as far side.

What colour would the sky appear to an astronaut standing on the “far side” of the Moon and why?

(a) blue, as the Moon’s atmosphere scatters sunlight just like Earth

(b) white, as the Moon’s surface reflect all the light that falls on it

(d) black, as sunlight does not fall on the far side of the Moon

View Answer

Ans. (c) black, as there is no atmosphere on Moon to scatter sunlight

15. Plants receive energy from the Sun which they utilise for several processes.

The energy utilized for which of the following plant processes gets transferred to the next trophic level that consumes plants?

(a) only growth

(b) only respiration and transport of substances

(d) all – growth, photosynthesis, respiration and transport of substances

View Answer

Ans. (a) only growth

16. The action of which among the following is crucial to the formation of ozone?

(a) humans

(b) sunlight

(d) chlorofluorocarbons

View Answer

Ans. (b) sunlight

Question No. 17 to 20 consist of two statements – Assertion (A) and Reason (R). Answer these questions:

17. Assertion (A): Zinc oxide can be reduced to zinc metal on heating with carbon.

Reason (R): Carbon is less reactive than zinc.

a) Both A and R are true, and R is the correct explanation of A.

b) Both A and R are true, and R is not the correct explanation of A.

c) A is true but R is false.

d) A is false but R is true.

View Answer

Ans. c) A is true but R is false.

18. Assertion (A): Variations always provide a survival advantage to an organism.

Reasons (R): Variations can be caused due to incorrect DNA copying.

a) Both A and R are true, and R is the correct explanation of A.

b) Both A and R are true, and R is not the correct explanation of A.

c) A is true but R is false.

d) A is false but R is true.

View Answer

Ans. d) A is false but R is true.

19. Assertion (A): Iron filings scattered around a straight current carrying conductor in a plane perpendicular to the length of the conductor, arrange themselves in concentric circles.

Reason (R): Magnetic field has both magnitude and direction.

a) Both A and R are true, and R is the correct explanation of A.

b) Both A and R are true, and R is not the correct explanation of A.

c) A is true but R is false.

d) A is false but R is true.

View Answer

Ans. b) Both A and R are true, and R is not the correct explanation of A.

20. Assertion (A): Omnivores receive 10% of their energy from the trophic level below them.

Reason (R): An omnivore is always in the trophic level just above herbivores.

a) Both A and R are true, and R is the correct explanation of A.

b) Both A and R are true, and R is not the correct explanation of A.

c) A is true but R is false.

d) A is false but R is true.

View Answer

Ans. c) A is true but R is false.

Section B

Question No. 21 to 26 are very short answer questions

21. (a) Write the balanced chemical equation for the reaction that is prevented by storing potassium metal under kerosene.

View Answer

Ans. (a) 4 K + O₂ —> 2 K₂O

(b) Identify the type of chemical reaction that is prevented.

View Answer

Ans. combination reaction OR oxidation reaction

22. Ravi cultivated mustard, a plant with bisexual flowers, on his farm. His plants were diseased due to a gene defect and therefore had reduced yield. Ravi removed the stamens from the diseased plants and also planted fresh disease-free mustard plants where he removed the pistils.

How will Ravi’s strategy help in improving the yield of mustard?

View Answer

Ans. – Ravi made the bisexual flower unisexual thereby encouraging crosspollination instead of self-pollination.

– Cross-pollination will increase variation and thereby the chances of having more disease-free offspring.

23. A plant X was enclosed in a glass jar with some lizards. A similar plant Y was enclosed in another glass jar but without lizards. Both the jars are kept under the same light conditions for a few hours. Which plant is likely to photosynthesize more and why?

View Answer

Ans. – Plant X

– Due to respiration of the lizard, the amount of carbon dioxide will increase leading to a higher amount of photosynthesis.

Proteinuria is a condition in which significant amounts of protein can be detected in urine. Which process in the nephron is likely to be affected causing proteinuria? Justify

View Answer

Ans. – Filtration OR selective reabsorption by the nephron may not be functioning properly.

– Improper filtration will lead to proteins getting filtered even though they are not waste.

After filtration, useful substances such as proteins may not be getting reabsorbed.

(a) What type of mirrors are generally used to make search mirrors?

View Answer

Ans. convex mirror

(b) With the help of a ray diagram describe the nature of image formed by the type of mirror identified in (a).

View Answer

Ans. virtual, erect and diminished

25. Ramya wants to measure the current flowing through the circuit shown below.

Which among the four ammeters can she use for the same? Show your calculations.

View Answer

Ans. From Ohm’s law we have

V = IR

I = V/R

given V = 12 V and R₁ = 2 ohm, R₂ = 8 ohm and R₃ = 4 ohm

Therefore,

net resistance R = R₁ + (R₂ x R₃)/ (R₂ + R₃)

= 2 + (8 x 4/8 + 4)

= 2 + 32/12

= 2 + 2.66

R = 4.66 ohm

I = 12/4.66

I = 2.58 A

– She can use ammeter S to measure the current in the circuit

A helical coil whose length is greater than its diameter is connected to a battery as shown below.

(a) How does the magnetic field at point P compare with the magnetic field at point Q? Justify your answer.

View Answer

Ans. – The magnetic field at P and Q is the same.

– because the magnetic field lines inside the helical coil of wire which behaves like a solenoid is uniform/in the form of parallel straight lines.

(b) State one way in which the strength of the magnetic field inside a current carrying helical coil can be changed?

View Answer

Ans. – increasing/decreasing the number of turn in the coil

– increasing/decreasing the current through the coil

26. Shown below are two food pyramids.

The pyramid representing the land ecosystem is traditional with producers being greater in mass than primary consumers and so on. Sometimes, in aquatic ecosystems, an inverted pyramid exists. Here, the total mass of producers (phytoplankton) is much smaller than the top consumers (big fishes).

(a) Which level is likely to have the most amount of energy in such an aquatic ecosystem? Give a reason to support your answer.

View Answer

Ans. – phytoplankton

– Producers will still have the highest amount of energy captured from sunlight which will continue to reduce as we move towards the top of the pyramid

(b) Such aquatic ecosystems are considered to be unstable. Justify this statement.

View Answer

Ans. Since the total mass in the lower trophic level is lesser there will be lesser food available to higher trophic levels causing organisms to die sooner than usual.

Section C

Question No. 27 to 33 are short answer questions

27. Equal sized bars of aluminium and iron are exposed to the environment as shown below

Which of them is likely to corrode till the level marked by the line FIRST? Justify your answer.

View Answer

Ans. – The iron bar will corrode till the level marked by the line first.

– Iron gets oxidised on exposure to air and moisture. The layer of rust formed on the surface allows air and moisture to pass through and reach the metal, causing corrosion to continue.

– Aluminium gets oxidised on exposure to air. The layer of oxide formed on the surface forms a protective coating that prevents air from reaching the metal and thus prevents further corrosion.

28. Which of them is likely to corrode till the level marked by the line FIRST? Justify your answer.

(a) Identify any two pairs of elements that will react to form compounds by a transfer of electrons.

View Answer

Ans. – Q and R

– Q and U

– T and R

– T and U

(b) Write the molecular formula of the compounds formed by the pairs of elements identified in (a).

View Answer

Ans. – Q₂R

– QU

– TR

– TU₂

A metal X is obtained from its chloride salt by exposure to sunlight.

(a) In which section of the reactivity series of metals- top, middle or bottom, is it likely to be placed? Justify your answer.

View Answer

Ans. – Metals at the bottom of the reactivity series are the least reactive. They occur in their free state; their compounds are unstable and hence easily converted to metal.

(b) Identify the type of reaction the chloride salt of metal X undergoes on exposure to sunlight.

View Answer

Ans. photolytic decomposition

29. In animals, hormones can be secreted by one organ and can act on multiple organs. Justify this statement by explaining the effect of a single animal hormone on three organs.

View Answer

Ans. – Adrenaline induces the sweat glands to produce more sweat.

– It acts on the heart to increase the contraction of its muscles/pumping causing improved oxygen delivery.

– It acts on blood vessels of the digestive system constricting them.

30. If two pea plants having round and green seeds (RRGg) are crossed, identify the percentage of the following with respect to the F1 generation:

(a) gametes having both the round and yellow seed traits

View Answer

Ans. (a) 50%

(b) offspring having the same genotype as the parents

View Answer

Ans. (b) 50%

View Answer

Ans. (c) 75%

31. Absolute refractive indices of two media P and Q are 1.33 (nP) and 2.52 (nQ) respectively. The speed of light in medium P is 2 x 108 m/s.

(a) What would be the speed of light in medium Q (VQ)?

View Answer

Ans. n_P = (Speed of light in vacuum/ speed of light in medium P)

n_q= (Speed of light in vacuum/ speed of light in medium Q)

Therefore,

n_P/n_Q = V_Q/V_P

= 1.33/2.52 = V_Q / 2 x 10⁸

V_Q= (1.33 x 2 x 10⁸)/ 2.52 = 1.056 x 10⁸m/s

(b) If the angle of incidence for a ray of light travelling from medium P to Q is 0°, then what will be the path of light in the medium Q?

View Answer

Ans. the ray will travel undeviated through the medium Q

32. Kaveri conducted an experiment to study the energy efficiency of different bulbs. She connected a bulb A having a resistance of 100 ohms to a 240 V power supply in a laboratory.

(a) How much energy will be consumed by the bulb, if it is kept ON for 4 hours each day for a week? Express your answer in kJ.

View Answer

Ans. (a) Given V = 240 V and R = 100 ohms

Therefore,

Power (P) = V²/R = (240)²/100 = 576 W

Energy consumed by bulb A = P × t

E = 576 x 4 x 7 × 60 × 60

E = 58,060.8 kJ

(b) Kaveri connects another similar bulb B in series with bulb A and connects the combination to a 240 V supply. Will there be any change in the brightness with which bulb A glows now? Explain mathematically.

View Answer

Ans. (b) When bulbs A and B are connected in series:

R_net = R1 + R2

= 100 + 100

R_net = 200 ohms

Total power consumed by bulb A when connected in series with bulb B

P_tot = V²/R_net = (240)²/200 = 288 W

P_A’ = P_tot/2 = 144 W

Power consumed by bulb A when connected without bulb B to 240 V

P_A= V²/R = (240)²/100 = 576 W

As P_A’ < P_A , the brightness of the bulb A decreases when connected in series with bulb B.

33. (a) Vijaya connects three bulbs P, Q and R is series with a battery in two different ways using identical conducting wires as shown below. She notices that in case I all three bulbs glow but in case II only the bulbs P and R continue to glow. What could be the reason for the bulb Q to not glow in case II? Explain.

View Answer

Ans. The current will flow through the additional wire that connects the points L and M (avoiding the bulb) as it offers a path of least/lower resistance as compared with the bulb

(b) Two resistances when connected in parallel give a combined resistance of 10/3 ohms. When the same two resistors are connected in series, the combined resistance becomes 15 ohms. Calculate the individual resistance of each resistor.

View Answer

Ans. 3/10 = 1/R1 + 1/R2 ………………. (1)

R₁ + R₂ = 15, R₁ = 15 – R₂

Substituting in (1)

3/10 = (15 – R₂ + R₂)/ (15 – R₂) R₂

15R₂ – R₂ ² = 150/3 = 50

R₂ ² – 15 R₂+50 = 0

R₂ = 10 ohm, R₁ = 5 ohm

R₁ = 10 ohm, R₂ = 5 ohm

Section – D

Question No. 34 to 36 are long answer questions.

34. A carbon compound P has six carbon atoms and twelve hydrogen atoms.

(a) Is P a saturated or unsaturated carbon compound. Justify your answer by drawing the structural formula.

View Answer

Ans. Compound P may be either saturated or unsaturated

– saturated compound: cyclohexane

– unsaturated compound: 2-hexene

[Accept any correct structural isomer]

(b) Describe a test that can be used to determine if compound P is saturated or unsaturated.

View Answer

Ans. burning the compound in an excess of air will produce a sooty flame if it is unsaturated and a clean flame if it is saturated

View Answer

Ans. carbon dioxide and water

A carbon compound P is found to be neutral when tested with red and blue litmus. A gas, that burns with a ‘pop’ sound, is produced when a metal reacts with carbon compound P.

(a) Write the chemical equation for the reaction.

View Answer

Ans. 2 Na + 2 CH₃ – CH₂OH —> 2 CH₃ – CH₂O^–Na⁺ + H₂

(b) The carbon compound P is heated with concentrated sulphuric acid to produce carbon compound Q.

(i) Write the chemical equation for the reaction.

View Answer

Ans. CH₃ – CH₂OH —> CH₂ = CH₂ + H₂O

(ii) Describe the type of flame that Q produces on combustion.

View Answer

Ans. Compound Q (ethylene) burns with a yellow flame with black smoke.

(c) What is likely to be observed on heating compound P with ethanoic acid with an acid as catalyst? Write the chemical equation for the reaction.

View Answer

Ans. A compound with a fruity smell will be produced.

35. (a) Certain specialised cells in animals called stem cells have the ability to divide and differentiate into different cell types. This helps in the replacement of a damaged organ.

Name and explain two methods of asexual reproduction that are similar to stem cells and occur mostly in multicellular organisms.

View Answer

Ans. – Regeneration

– In this process, if an individual organism is cut or broken up into many pieces, many of these pieces grow into separate individuals.

– Budding

– In budding, a small outgrowth or bud forms on the parent organism, which eventually detaches and develops into a new individual.

(b) Identify TWO pairs of reproductive organs in males and females that are functionally similar to each other. Justify.

View Answer

Ans. – testes and ovaries

– Both structures perform the function of producing gametes and hormones crucial for reproduction

– vas deferens and fallopian tube

– Both structures are responsible for carrying the gamete to the site of fertilisation.

(a) Sagar saw a beautiful rose and smelled it. As he was smelling it, he happened to touch a thorn and pull his hand away.

State TWO differences and similarities each in the way the nervous system performs the two actions.

View Answer

Ans. Similarities:

– In both cases, the signal is initiated by receptors located at the specific sense organ.

– In both cases, neurotransmitters are released and accepted by neurons to carry the impulse.

Differences:

– The action of smelling the rose is voluntary whereas pulling the hand away is involuntary in nature.

– While smelling the rose, the nerve impulse reaches the brain and back whereas on touching a thorn the nerve impulse travels only to the spinal cord and back.

(b) Are all involuntary actions reflex actions? Justify.

View Answer

Ans.- No

– Most involuntary actions do not require a stimulus to occur as is necessarily required in the case of a reflex action.

36. Savera passed a beam of white light through a series of equilateral prisms as shown.

(a) What colour(s) will be seen on the screen?

View Answer

Ans. VIBGYOR

– violet

– indigo

– blue

– green

– yellow

– orange

– red

(b) Copy the diagram above and draw the beam entering Prism 1 and emerging from Prism 3 and falling on the screen.

View Answer

Ans.

View Answer

Ans. – dispersion

– refraction

(a) Rupal suffers from myopia. Where would the image form in her eye?

View Answer

Ans. in front of the retina

(b) Name the type of lens that is generally used to correct myopia.

View Answer

Ans. concave lens

(c) Rupal underwent cataract surgery and her eye lens was replaced with an artificial lens with a fixed focal length, made of a plastic material, silicone. State one likely visual disadvantage that Rupal is likely to experience as compared to a person who has normal eyesight.

View Answer

Ans. The person would not have the power of accommodation

(d) Identify the parts of the eye labeled in the diagram from the descriptions given below by writing the labels as your answer.

(i) It helps in changing the focal length of the lens.

View Answer

Ans. R

(ii) It causes most of the refraction of the light entering the eye.

View Answer

Ans. Q

(iii) It controls the amount of light entering the eye.

View Answer

Ans. P

(iv) It acts as a screen on which the image is formed.

View Answer

Ans. S

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

37. Given below is a four carbon skeleton of a hydrocarbon compound.

(a) Fill in the hydrogen atoms/bonds to form:

(i) a saturated hydrocarbon

View Answer

Ans.

(ii) an unsaturated hydrocarbon

View Answer

Ans.

(b) If the four-carbon skeleton is of a straight chained alkene, draw the structures of all the possible compounds.

View Answer

Ans.

If the four-carbon skeleton is of a straight chained alkyne:

(i) How many carbon atoms may NOT be bonded to any hydrogen atoms?

View Answer

Ans. one or two

(ii) How many hydrogen atoms will there be in the compound?

View Answer

Ans. six

38. Ram and Asha were a married couple where Ram had normal vision whereas Asha could not see some colours (colour-blind). They give birth to five children – 3 sons and 2 daughters. Of these, all sons were colour-blind while both daughters had normal vision.

(a) Using a reason to support your answer for each, identify if the trait for colour blindness is:

(i) recessive or dominant?

View Answer

Ans. (a) (i) – Yes, it is recessive.

– Since the trait does not express itself in all children, it is likely to be a recessive trait.

(ii) linked to the X chromosome or Y chromosome?

View Answer

Ans. – Yes, it is X-linked.

– Yes, since both male children received the X chromosome from the mother who is colour blind, it is likely to be linked to the X-chromosome.

(b) Based on (a), what is the genotype of Ram and Asha with respect to the colour-blind trait? Draw a Punnett square to show the cross.

View Answer

Ans.

– Ram – XY

– Asha – X^cX^c

Puneett square

	X	Y
X^C	X^CX	X^CY
X^C	X^CX	X^CY

If one of the sons gets married to a girl who is heterozygous for the colourblind trait, what is the possibility of their son being colour-blind? Show the cross.

View Answer

Puneett square

	X^C	Y
X^C	X^CX^C	X^CY
X	X^CX^C	XY

50% possibility of the son being colour-blind

39. Four resistors, a voltmeter and a battery are connected in a circuit as shown below.

(a) What is the net resistance in the circuit?

View Answer

Ans. The net resistance is: R₁ + (1/R₂ + 1/R₃) + R₄

= 15 + 10 + 15 R

= 40 Ω

(b) How much potential difference will the voltmeter connected across the resistor R4 measure?

View Answer

Ans. Voltage drop across R₄ = Net current x R₄

Net current = V/R

= 20/40

= 0.2 A

Voltage drop across R₄ = 0.2 x 15

= 3 V

What is the power dissipated by the resistor R1?

View Answer

Ans. Power dissipated by the resistor R1 is given by:

P = I²R₁

I = V/R

= 20/40

I = 0.2 A

Therefore,

Power = (0.2)² x 15 = 0.6 W

View Answer

Ans. – net current will decrease

– because R3 is connected in parallel and removing it will increase the net resistance in the circuit thereby reducing the net current.

Class X – Science Sample Paper – 1