10 CBSE Science Board Exam 2024: February 2024

10 Class Science Board Exam 2024:

Note:

1. Please check that this question paper contains 23 printed pages.
2. Please check that this question paper contains 39 questions.
3. Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.
4. Please write down the Serial Number of the question in the answer-book before attempting it.
5. 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 am. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer- book during this period.

School Name:	New Delhi 110085 India
Class:	10th Standard (CBSE)
Subject:	Social Science Standard
Time Duration:	03 Hours
Maximum Marks:	80
Date:	~ February 2024

General Instructions:

Read the following instructions very carefully and strictly follow them:

1. This question paper comprises 39 questions. All questions are compulsory.
2. This question paper is divided into five sections – A, B, C, D and E.
3. Section A – Question Nos. I to 20 are multiple choice questions. Each question carries 1 mark.
4. Section B – Question No. 21 to 26 are very short answer type questions. Each question carries 2 marks. Answers to these questions should be in the range of 30 to 50 words.
5. Section C – Question Nos. 27 to 33 are short answer type questions. Each question carries 3 marks. Answers to these questions should be in the range of 50 to 80 words.
6. Section D – Question Nos. 34 to 36 are long answer type questions. Each question carries 5 marks. Answers to these questions should be in the range of 80 to 120 words.
7. Section E – Question Nos. 37 to 39 are of 3 source-based/case-based units of assessment carrying 4 marks each with sub-parts.
8. There is no overall choice. However, an internal choice has been provided in some sections. Only one of the alternatives has to be attempted in such questions.

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 the incorrect response.

Question: 01. Select from the following a decomposition reaction in which source of energy for decomposition is light:

1. 2FeSO₄ —–> Fe₂0₃+ SO₂ + SO₃
2. 2H₂O —–> 2H₂ + O₂
3. 2AgBr —–> 2Ag + Br₂
4. CaCO₃ —–> CaO + CO₂

Question: 02. When 2ml of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as:

1. NaOH + Zn —–> NaZnO₂ + H₂O
2. 2NaOH + Zn —–> Na₂ZnO₂ + H₂
3. 2NaOH + Zn —–> NaZnO₂ + H₂
4. 2NaOH + Zn —–> Na₂ZnO₂ + H₂0

Question: 03. MnO₂ + 4HCl —–> MnCl₂ + 2H₂0 + Cl₂
The reaction given above is a redox reaction because in this case:

1. MnO₂ is oxidised and HCI is reduced.
2. HCl is oxidised.
3. MnO₂ is reduced.
4. MnO₂ is reduced and HCl is oxidised.

Question: 04. Consider the following compounds:

FeSO₄; CuSO₄; CaSO₄; Na₂CO₃
The compound having maximum number of water of crystallization in its crystalline form in one molecule is:

1. FeSO₄
2. CuSO₄
3. CaSO₄
4. Na₂CO₄

Question: 05. In a nerve cell, the site where the electrical impulse is converted into a chemical signal is known as:

1. Axon
2. Dendrites
3. Neuromuscular junction
4. Cell body

Question: 06. A metal and a non-metal that exists in liquid state at the room temperature are respectively:

1. Bromine and Mercury
2. Mercury and Iodine
3. Mercury and Bromine
4. Iodine and Mercury

Question: 07. At what distance from a convex lens should an object be placed to get an image of the same size as that of the object on a screen?

1. Beyond twice the focal length of the lens.
2. At the principal focus of the lens.
3. At twice the focal length of the lens.
4. Between the optical centre of the lens and its principal focus.

Question: 08. Carbon compounds:

1. are good conductors of electricity.
2. are bad conductors of electricity.
3. have strong forces of attraction between their molecules.
4. have weak forces of attraction between their molecules.

The correct statements are:

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

Question: 09. Oxides of aluminium and zinc are:

1. acidic
2. basic
3. amphoteric
4. neutral

Question: 10. Chromosomes:

1. carry hereditary information from parents to the next generation.
2. are thread-like structures located inside the nucleus of an animal cell.
3. always exist in pairs in human reproductive cells.
4. are involved in the process of cell division.

The correct statements are:

1. (i) and (ii)
2. (iii) and (iv)
3. (i), (i) and (iv)
4. (i) and (iv)

Question: 11. Consider the following statements:

1. The sex of a child is determined by what it inherits from the mother.
2. The sex of a child is determined by what it inherits from the father.
3. The probability of having a male child is more than that of a female child.
4. The sex of a child is determined at the time of fertilisation when male and female gametes fuse to form a zygote.

The correct statements are:

1. (i) and (iii)
2. (ii) and (iv)
3. (iii) and (iv)
4. (i), (iii) and (iv)

Question 12. Which one of the following organs is NOT a part of the human female reproductive system?

1. Ovary
2. Uterus
3. Vas deferens
4. Fallopian tube

Question 13. In which of the following organisms, multiple fission is a means of asexual reproduction?

1. Yeast
2. Leishmania
3. Paramoecium
4. Plasmodium

Question 14. In bifocal lenses used for the correction of presbyopia:

1. the upper portion is of convex lens for the near vision and lower part is of concave lens for the distant vision.
2. the upper portion is of convex lens for distant vision and lower part is of concave lens for near vision.
3. the upper portion of the concave lens is for the near vision and the lower part is of the convex lens for the distant vision.
4. the upper portion is of concave lens for distant vision and lower part is of convex lens for near vision.

Question 15. The pattern of the magnetic field produced inside a current carrying solenoid is:

Question 16. Identify the food chain in which the organisms of the second trophic level are missing:

1. Grass, goat, lion
2. Zooplankton, Phytoplankton, small fish, large fish
3. Tiger, grass, snake, frog
4. Grasshopper, grass, snake, frog, eagle

For Question. Nos. 17 to 20, two statements are given:

One labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

1. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
2. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
3. Assertion (A) is true, but Reason (R) is false.
4. Assertion (A) is false, but Reason (R) is true.

Question 17.

Assertion (A): The rainbow is a natural spectrum of sunlight in the sky.
Reason (R): Rainbow is formed in the sky when the sun is overhead and water droplets are also present in air.

Question 18.

Assertion (A): Hydrogen gas is not evolved when zinc reacts with nitric acid.
Reason (R): Nitric acid oxidises the hydrogen gas produced to water and itself gets reduced.

Question 19.

Assertion (A): Accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain.
Reason (R): Harmful chemicals are sprayed on the crops to protect them from diseases and pests.

Question 20.

Assertion (A): The rate of breathing in aquatic organisms is much faster than in terrestrial organisms.
Reason (R): The amount of oxygen dissolved in water is very high as compared to the amount of oxygen in air.

Section – B

Question 21.

(A)

1. Write the significance of the peripheral nervous system in human beings.
2. How is the human brain protected from mechanical injuries and shocks?

(B)

Name one directional growth movement each in response to chemicals and water in plants. Write an example for each of them.

Question 22.

1. Give a reason why herbivorous animals have longer, small intestines than carnivorous animals?
2. Although ‘Pepsin’ and ‘Trypsin’ are protein digesting enzymes yet they differ from each other. Justify this statement by giving one.

Question 23.

Translate the following statement into a balanced chemical equation.
“When barium chloride reacts with aluminium sulphate, aluminium chloride and barium sulphate are formed.”
State the type of this reaction giving reason to justify your answer.

Question 24.

1. Two magnetic field lines do not intersect each other. Why?
2. How is a uniform magnetic field in a given region represented ? Draw a diagram in support of your answer.

Question 25.

Draw the pattern of the magnetic field lines due to a straight current carrying conductor indicating the direction of current in the conductor and the direction of the corresponding magnetic field lines.

Question 26.

An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position of the image formed by the mirror.

Section – C

Question 27.

(A) Plants + Deer > Lion 3

In the given food chain, what will be the impact of removing all the organisms of second trophic level on the first and third trophic level ? Will the impact be the same for the organisms of the third trophic level in the above food chain if they were present in a web ? Justify.

OR

(B) A gas ‘X’ which is a deadly poison is found at the higher levels of the atmosphere and performs an essential function.

Name the gas and write the function performed by this gas in the atmosphere. Which chemical is linked to the decrease in the level of this gas ? What measures have been taken by an international organization to check the depletion of the layer containing this gas?

Question 28. Name and state the rule to determine the direction of a:

1. magnetic field produced around a current carrying straight conductor.
2. force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it.

Question 29. Study the diagram given below and answer the questions that follow:

1. Name the defect of vision represented in the diagram. Give reason for your answer.
2. List two causes of this defect.
3. With the help of a diagram show how this defect of vision is Y corrected.

Question 30. Define reflex action. With the help of a flow chart show the path of a reflex action such as sneezing.

Question 31. 

1. Which organisms have a three-chambered heart? Why do they have 3 three-chambered hearts?
2. List two functions of lymph.

Question 32.

A compound which is prepared from gypsum has the property of hardening when water is mixed in right quantity with it:

1. Write common name and the chemical name of this compound.
2. Give chemical equation for its preparation.
3. List its two uses.

Question 33.

1. Define a decomposition reaction. Write a chemical equation for the reaction that occurs when lead nitrate is heated strongly in a boiling tube.
2. In electrolytic decomposition of water two gases are liberated at the electrodes. Give the mass ratio of the gas liberated at the cathode and at the anode.

Section – D

Question 34.

(A)

(i) State whether the currents and potential difference in all the bulbs will be same or different when in a circuit three bulbs of:

1. same wattage is connected in series.
2. same wattage is connected in parallel.
3. different wattages are connected in series.
4. different wattages are connected in parallel.

(ii) Two identical resistors of 24 Q each are connected to a battery of 6V. Calculate the ratio of the power consumed by the resulting combinations with(a) minimum resistance and (b) maximum resistance.

OR

(B)

Draw a schematic diagram of a circuit consisting of a battery of six 2V cells, a 6 Q resistor, a 12 Q resistor and a 18 Q resistor and a plug key all connected in series. Calculate the following (when key is closed) :

1. Electric current flowing in the circuit.
2. Potential difference across 18 Q resistor.
3. Electric power consumed in 18 Q resistor.

Question 35.

(A)

1. Define a homologous series of carbon compounds.
2. Why are the melting and boiling points of C₄H₈ higher than that of C₃H₆ or C₂H₄?
3. Why do we NOT see any gradation in chemical properties of homologous series compounds ?
4. Write the name and structures of (i) aldehyde and (ii) ketone with molecular form C₃H₆O.

OR

(B)

1. Write the name and structure of an organic compound ‘X’ having two carbon atoms in its molecule and its name is suffixed with ‘ol’.
2. What happens when ‘X’ is heated with excess concentrated sulphuric acid at 443 K ? Write a chemical equation for the reaction stating the conditions for the reaction. Also state the role played by concentrated sulphuric acid in the reaction.
3. Name and draw the electron dot structure of hydrocarbons produced in the above reaction.

Question 36.

(A)

1. Name three techniques/devices used by human females to avoid pregnancy. Mention the side effects caused by each.
2. What will happen if a human female (a) fertilisation takes place, (b) an egg is not fertilised?

OR

(B)

1. Draw a diagram showing spore formation in Rhizopus and label the (a) reproductive and (b) non-reproductive parts. Why does Rhizopus not multiply on a dry slice of bread?
2. Name and explain the process by which reproduction takes place in Hydra.

Section – E

Question No. 37-39 are source-based / case-based question with 2 to 3 short sub-parts. Internal choice is provided in one of these sub-parts:

Question 37. Mendel worked out the rules of heredity by working on garden pea using a number of visible contrasting characters. He conducted several experiments by making a cross with one or two pairs of contrasting characters of pea plant. On the basis of his observations he gave some interpretations which helped to study the mechanism of inheritance.

1. When Mendel crossed pea plants with pure tall and pure short characteristics to produce F1, which two observations were made by him in F1 plants?
2. Write one difference between dominant and recessive traits.
3. (A) In across with two pairs of contrasting characters
   RRYY X rryy
   (Round Yellow) (Wrinkled Green)
   Mendel observed 4 types of combinations in F2 generation. By which method did he obtain F2 generation? Write the ratio of the parental combinations obtained and what conclusions were drawn from this experiment.

OR

(iii) (B) Justify the statement:
“It is possible that a trait is inherited but may not be expressed.”

Question 38. Study the data given below showing the focal length of three concave mirrors A, B and C and the respective distances of objects placed in front of the mirrors :

1. In which one of the above cases the mirror will form a diminished image of the object? Justify your answer.
2. List two properties of the image formed in case
3. (A) What is the nature and size of the image formed by mirror C? Draw a ray diagram to justify your answer.

OR

3. (B) An object is placed at a distance of 18 cm from the pole of a concave mirror of focal length 12 cm. Find the position of the image formed in this case.

Question 39. The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining.

1. What is the cathode and anode made of in the refining of copper by this process?
2. Name the solution used in the above process and write its formula.
3. (A) How copper gets refined when electric current is passed in the electrolytic cell?

OR

3. (B) You have two beakers ‘A’ and ‘B’ containing copper sulphate solution. What would you observe after about 2 hours if you dip a strip of zinc in beaker ‘A’ and a strip of silver in beaker ‘B’? Give reason for your observations in each case.