Sample Question Paper for class 10th

Science (Annual Examination)

Board Examination (2020-21)

Class - X

Subject- Science (086)

Time: 3 hours M.M.: 80

General Instructions:

1. The question paper comprises four sections A, B, C and D. There are 36 questions in the question paper. All questions are compulsory.

2. Section–A - question no. 1 to 20 - all questions and parts thereof are of one mark each. These questions contain multiple choice questions (MCQs), very short answer questions and assertion - reason type questions. Answers to these should be given in one word or one sentence.

3. Section–B - question no. 21 to 26 are short answer type questions, carrying 2 marks each. Answers to these questions should in the range of 30 to 50 words.

4. Section–C - question no. 27 to 33 are short answer type questions, carrying 3 marks each. Answers to these questions should in the range of 50 to 80 words.

5. Section–D – question no. - 34 to 36 are long answer type questions carrying 5 marks each. Answer to these questions should be in the range of 80 to 120 words.

6. There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.

7. Wherever necessary, neat and properly labeled diagrams should be drawn.

Section-A

Why does an aluminium vessel lose its shine so soon after use?

Why does zinc plate develop holes when placed in copper sulphate solution for a few hours/days?

Solution A, B, C and D has pH values 3, 4, 5 and 6 respectively. Arrange them in increasing order of acidic character. Give reason to support your answer.

Why is respiration considered as an exothermic reaction?

When a white light passes through a prism, which colour deviates the least and which colour deviates the most?

An object is placed in front of a convex mirror of focal length 30 cm and the image formed is half the size of object. Find the position of image from the mirror.

Under what condition will a mirror have magnification +0.5?

What is lateral inversion? Explain with suitable example.

In the arrangement shown in figure there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted in the circuit. Later the key is inserted and then removed shortly after.

What are the two observations that can be noted from the galvanometer reading?

A student while studying the force experienced by a current carrying conductor in a magnetic field records the following observation. Which observation is correct? Justify.

(i) The force experienced by the conductor increases as the current is increased.

(ii) The force experienced by the conductor decreases as the strength of the magnetic field is increased.

How many electrons will flow for the charge 4C? (Charge of 1 electron = 1.6 x 10^-19 C)

Copper wire has resistance R. If the wire is doubled on it. Find the new resistance in terms of original resistance?

10.

Mention any one point of difference between Pepsin and Trypsin.

11.

Name a common nutrient that is absorbed in the small intestine and reabsorbed by the kidney tubules.

What is role of hydrochloric acid in human digestive system?

12.

Name the two devices which release the ozone depleting substances.

Write the main function of ozone in the upper atmosphere.

13.

What are the end products of anaerobic respiration in yeasts?

For question numbers 14, 15 and 16, two statements are given- one labeled Assertion (A) and the other labeled

Reason (R). Select the correct answer to these questions from the codes

(a), (b), (c) and (d) as given below:

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

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

(d) A is false, but R is true.

14.

Assertion (A): Bleaching powder has a strong smell of chlorine.

Reason(R): Bleaching powder is a white powder and a strong oxidizing agent.

15.

Assertion (A) : Food chain is responsible for the entry of harmful chemicals in our bodies.

Reason (R) : The length and complexity of food chains vary greatly.

Assertion (A) : Greater number of individuals are present in lower trophic levels.

Reason (R) : The flow of energy is unidirectional.

16.

Assertion (A) : Aquired characters are non-inheritable.

Reason (R) : Aquired characters generally affects the somatic cells and it is the germ cells that are passed on to the next generation.

Q. No 17 - 20 contain five sub-parts each. You are expected to answer any four sub parts in these questions.

17.

Read the following and answer any four questions from 17 (i) to 17 (v).

All living cells require energy for various activities. This energy is available by the breakdown of simple carbohydrates either using oxygen or without using oxygen.

1x4

17(i).

Energy in the case of higher plants and animals is obtained by

(a) Breathing

(b) Tissue respiration

(d) Digestion of food

17(i).

The graph below represents the blood lactic acid concentration of an athlete during a race of 400 m and shows a peak at point D.

Y-axis-Blood lactic acid concentration (nmol/litre)

Lactic acid production has occurred in the athlete while running in the 400 m race. Which of the following processes explains this event?

(a) Aerobic respiration

(b) Anaerobic respiration

(d) Breathing

17(iii).

The characteristic processes observed in anaerobic respiration are

(i) presence of oxygen

(ii) release of carbon dioxide

(iii) release of energy

(iv) release of lactic acid

(a) (i) ,(ii) only

(b) (i), (ii), (iii) only

(d) (iv) only

17(iv).

Study the table below and select the row that has the incorrect information.

Aerobic Anaerobic

(a) Location Cytoplasm Mitochondria

(b) End Product CO₂ and H₂0 Ethanol and CO₂

(d) Oxygen Needed Not needed

17(v).

Study the graph below that represents the amount of energy supplied with respect to the time while an athlete is running at full speed.

Choose the correct combination of plots and justification provided in the following table.

Plot A Plot B Justification

(a) Aerobic Anaerobic Amount of energy is low and inconsistent in aerobic and

high in anaerobic

(b) Aerobic Anaerobic Amount of energy is high and consistent in aerobic and low

in anaerobic

(d) Anaerobic Aerobic Amount of energy is high and inconsistent in anaerobic and

low in aerobic

18.

Read the following passage and answer any four questions from 18(i) to 18(v).

Modern periodic table arranges the elements in the increasing order of atomic numbers. It has 18 groups and 7 periods. Atomic numbers are consecutive in a period and increases in group in a pattern. 78% of elements are metals, about 20% elements are non- metals and few elements like B, Si, Ge, As are metalloids. Metallic character increases down the group but decreases along the period from left to right. The physical and chemical properties vary periodically with their atomic numbers.

Periodic trends are observed in atomic size, metallic and non-metallic character and valence. Oxides of metals are basic, some are amphoteric. Non-metals form acidic oxides, some form neutral oxides.

1x4

18(i).

Element X forms a chloride with the formula XCl₂, which is a solid with high melting point. X would most likely be in the same group of the Periodic table as

(a) Na (b) Mg (c) Al (d) Si

18(ii).

Which of the following metal forms amphoteric oxide?

(a) Copper (b) Silver (c) Aluminium (d) Iron

18(iii).

Considering the elements B, Al, Mg and K, the correct order of their metallic character is

(a) B>Al>Mg>K (b) Al>Mg>B>K

18(iv).

Which one among the following is an acidic oxide?
(a)Na2O
(b)CO
(c)CO2
(d) Al2O3

18(v).

Which of the following does not decrease while moving down the group of the periodic table?

(a) Atomic radius

(b) Metallic character

(d) Valence electrons

19.

Read the following and answer any four questions from 19 (i) to 19 (v).

A point object is placed on the principle axis of a concave mirror quite far away from the pole and is moved at a constant speed of 5 cm/s towards the pole. It is found out that object and image cross each other at a point which is at a distance 50 cm from the pole. Choose the correct answer.

1x4

19(i).

Focal length of mirror is

(a) 50 cm

(b) 35 cm

(d) 15 cm

19(ii).

Position of the image when the object is at a distance of 30 cm from the pole is

(a) 150 cm from the pole in front of the reflecting surface

(b) 120 cm from the pole behind the mirror

(d) 150 cm from the pole in front of the reflecting surface

19(iii).

Speed of the image w.r.t. mirror when the object is crossing the position which is at a distance 50 cm from the pole is

(a) 15 cm/s

(b) 12 cm/s

(d) 10 cm/s

19(iv).

Angle of incident ray with normal is 30⁰. The angle between incident ray and reflected ray is

(a) 60⁰

(b) 30⁰

(d) 45⁰

19(v).

The image formed by a concave mirror is

(a) Always real

(b) Always virtual

(d) Virtual if the object is at infinite

20.

Read the following and answer any four questions from 20 (i) to 20 (v).

A solenoid is a long helical coil of wire through which a current is run in order to create a magnetic field. The magnetic field of the solenoid is the superposition of the fields due to the current through each coil. It is nearly uniform inside the solenoid and close to zero outside and is similar to the field of a bar magnet having a north pole at one end and a south pole at the other depending upon the direction of current flow. The magnetic field produced in the solenoid is dependent on a few factors such as, the current in the coil, number of turns per unit length etc.

The following graph is obtained by a researcher while doing an experiment to see the variation of the magnetic field with respect to the current in the solenoid.

The unit of magnetic field as given in the graph attached is in milli-Tesla (mT) and the current is given in Ampere.

1x4

20(i).

What type of energy conversion is observed in a linear solenoid?

(a) Mechanical to Magnetic

(b) Electrical to Magnetic

(d) Magnetic to Mechanical

20(ii).

What will happen if a soft iron bar is placed inside the solenoid?

(a) The bar will be electrocuted resulting in short-circuit.

(b) The bar will be magnetised as long as there is current in the circuit.

(d) The bar will not be affected by any means.

20(iii).

The magnetic field lines produced inside the solenoid are similar to that of

(a) a bar magnet

(b) a straight current carrying conductor

(d) electromagnet of any shape

20(iv).

After analysing the graph a student writes the following statements.

I. The magnetic field produced by the solenoid is inversely proportional to the current.

II. The magnetic field produced by the solenoid is directly proportional to the current. III. The magnetic field produced by the solenoid is directly proportional to square of the current.

IV. The magnetic field produced by the solenoid is independent of the current. Choose from the following which of the following would be the correct statement(s).

(a) Only IV

(b) I, III and IV

(d) Only II

20(v).

From the graph deduce which of the following statements is correct.

(a) For a current of 0.8A the magnetic field is 13 mT.

(b) For larger currents, the magnetic field increases non-linearly.

(d) There is not enough information to find the magnetic field corresponding to 0.8A current.

Section-B

21.

Mention the site of complete digestion in our body? Name the end products formed on complete digestion of carbohydrates proteins and fats.

(a)Write the balanced chemical equation for the process of photosynthesis.

(b)When do the desert plants take up carbon dioxide and perform photosynthesis?

22.

How the transport of water in plants carried out?

23.

A white salt on heating decomposes to give brown fumes and a residue is left behind.

(a) Name the salt.

(b) Write the equation for the decomposition reaction.

24.

(a) Platinum, gold and silver are used to make jewellery.

(b) Why hydrogen gas is not evolved when calcium reacts with dilute nitric acid?

When carbon dioxide is passed through lime water, first it turns milky and on further passing the gas, milkiness disappears. Explain with the help of chemical equations.

25.

Why planets do not twinkle? Explain.

26.

(a) Define one ohm.

(b) How many 330 Ω resistors in parallel are required to carry 20 A on a 220 V line?

Section-C

27.

A cross was made between pure breeding pea plants, one with round and green seeds and other with wrinkled and yellow seeds.

(a)Write the phenotype of F₁ progeny. Give reason for your answer.

(b)Write the different types of phenotypes of F₂ progeny obtained along with their ratio when F₁ progeny was selfed.

A cross was carried out between a pure bred tall pea plant and a pure bred dwarf pea plant and F1 progeny was obtained. Later the F₁ progeny was selfed to obtain F₂ progeny. Answer the following questions:

(a)What is the phenotype of F₁ progeny and why?

(b)Give the phenotypic ratio of F₂ progeny.

(c )Why is the F₂ progeny different from the F₁ progeny?

28.

Plastic cups were used to serve tea in trains in early days- these could be returned to the vendors, cleaned and reused. Later, Kulhads were used instead of plastic cups. Now, paper cups are used for serving tea.

What are the reasons for the shift from Plastic to Kulhads and then finally to paper cups?

29.

List in tabular form three differences between arteries and veins.

30.

The following table shows as the position of six elements, A, B, C, D, E and F in the periodic table.

Groups

Periods

3 to 12

Use the above table to answer the following questions. Give reason to support your answer.

(a) Which element is a non-metal with valency 2?

(b)The hydroxide of which element is most basic.

31.

“pH has a great importance in our daily life”. Explain by giving three examples.

Give reasons for your answer:

(a) Some alkali metals can be cut with a knife.

(b) Metals like Na, K, Ca and Mg are never found in their free state.

32.

When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH. (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

33.

(a) Define dioptre.

(b) The refractive indices of glass and water with respect to vacuum are 3/2 and 4/3 respectively. If the speed of light in glass is 2 x 10⁸ m / s, find the speed of light in:

(i) Vacuum

(ii) Water

Section-D

34.

(a) Name a metal for each case-

(i) It does not react with cold as well as hot water but reacts with steam.

(ii) It does not react with any physical state of water.

(b) When calcium is added to water, the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so?

(c) An element reacts with oxygen to form an oxide which dissolves in dilute hydrochloric acid. The oxide also turns a solution of red litmus blue. Is the element a metal or a non-metal? Explain with the help of a suitable example.

(a) Atomic number is considered to be more appropriate parameter than atomic mass for classification of elements in a periodic table. Why?

(b) “Sodium hydrogen carbonate is basic salt”. Justify the statement. How is it converted to washing soda?

verified?

35.

(a) Redraw the following diagram of human-male reproductive system in note book. Label and write the one function of each of the following parts:

(i) Urethra (ii) Scrotum (iii) Vas deference (iv) Prostate gland

(b)What are the two roles of testosterone?

36.

Find out the following in the electric circuit given in figure.

(a) Effective resistance of two 8Ω resistors in the combination.

(b)Current flowing through 4 Ω resistor.

(d) Power dissipated in 4 Ω resistor.

(e) Difference in ammeter readings, if any.

(a)Two circular coils A and B are placed close to each other. If the current in the coil changed, will some current be induced in the coil B? Give reason.

(b) State the rule to determine the direction of :

(i) Magnetic field produced around a straight conductor- carrying current.

(ii) Force experienced by a current carrying straight conductor placed in a magnetic field, which is perpendicular to it.

(iii) Current induced in a coil due to its rotation in a magnetic field.