CBSE Std-10 Science — Practice Paper
CBSE Std 10 · Science
General instructions: Attempt all questions. Marks for each question are shown in the right margin. Internal choice, where given, is indicated by “OR”.
Section A
- 1.
When zinc reacts with dilute sulfuric acid, what type of chemical reaction occurs?
[1]- (a)A) Decomposition
- (b)B) Combination
- (c)C) Displacement
- (d)D) Neutralization
- 2.
Assertion (A): Covalent compounds generally have lower melting points than ionic compounds. Reason (R): Covalent compounds have weak intermolecular forces.
[1]- (a)A) Both A and R are true; R is the correct explanation of A
- (b)B) Both A and R are true; R is not the correct explanation of A
- (c)C) A is true but R is false
- (d)D) A is false but R is true
- 3.
Which of the following is a characteristic property of non-metals?
[1]- (a)A) They are good conductors of electricity
- (b)B) They form acidic oxides
- (c)C) They are ductile and malleable
- (d)D) They lose electrons easily
- 4.
Which element belongs to Group 18 of the periodic table?
[1]- (a)A) Oxygen
- (b)B) Nitrogen
- (c)C) Argon
- (d)D) Sodium
- 5.
The light-independent reactions of photosynthesis (Calvin cycle) occur in which part of the chloroplast?
[1]- (a)A) Thylakoid membrane
- (b)B) Stroma
- (c)C) Inner membrane envelope
- (d)D) Starch grain
- 6.
The functional unit of the nervous system is the:
[1]- (a)A) Synapse
- (b)B) Neuron
- (c)C) Dendrite
- (d)D) Axon
- 7.
Which organism reproduces asexually by budding?
[1]- (a)A) Amoeba
- (b)B) Spirogyra
- (c)C) Hydra
- (d)D) Planaria
- 8.
The correctly balanced equation for the complete combustion of methane is:
[1]- (a)A) CH₄ + O₂ → CO₂ + H₂O
- (b)B) CH₄ + 2O₂ → CO₂ + 2H₂O
- (c)C) 2CH₄ + O₂ → 2CO + 2H₂O
- (d)D) CH₄ + O₂ → C + 2H₂O
- 9.
Assertion (A): Lemon juice turns blue litmus paper red. Reason (R): Lemon juice contains citric acid, which is acidic in nature.
[1]- (a)A) Both A and R are true; R is the correct explanation of A
- (b)B) Both A and R are true; R is not the correct explanation of A
- (c)C) A is true but R is false
- (d)D) A is false but R is true
- 10.
Diamond and graphite are allotropes of carbon because:
[1]- (a)A) They have the same density
- (b)B) They are forms of the same element with different atomic structures
- (c)C) They have the same melting point
- (d)D) They dissolve in the same solvents
Section B
- 11.
Define an enzyme. State any two characteristics of enzymes.
[2] - 12.
Name the three main components of a reflex arc. In which direction does the impulse travel through them?
[2] - 13.
Differentiate between binary fission and mitosis as modes of asexual reproduction in unicellular organisms.
[2]
Section C
- 14.
Arrange the following metals in order of their decreasing reactivity: Cu, Mg, Al, Zn. Mention one application of the reactivity series.
[3] - 14.
State the main properties of carbon that make it unique. Explain why carbon forms four covalent bonds.
[3] - 15.
Explain how a salt is prepared by the reaction between an acid and a base. Write the general equation and give one example with observation.
[3] - 15.
Define pH. Explain how you would determine the pH of a solution using pH paper and a pH meter. Which method is more accurate and why?
[3] - 16.
State the periodic law. Explain how the periodic table is organized based on atomic numbers. Give two advantages of the periodic table.
[3] - 16.
Compare metallic and non-metallic elements with respect to: (i) the nature of their oxides, (ii) their tendency to lose or gain electrons, and (iii) their position in the periodic table.
[3]
Section D
- 17.
Explain the process of aerobic respiration in plants. Write the overall equation for aerobic respiration. How does it differ from anaerobic respiration in terms of location, ATP production, and end products?
[5] - 17.
Distinguish between photosynthesis and aerobic respiration by comparing: (i) the nature of the process (anabolic/catabolic), (ii) the site of occurrence, (iii) energy changes, (iv) inputs and outputs. Write the overall equations for both.
[5] - 18.
Define redox reactions. Explain the concepts of oxidation and reduction with suitable examples. Determine the oxidation states of all atoms in: (i) H₂SO₄ and (ii) CaCl₂.
[5] - 18.
What are displacement reactions? Distinguish between single displacement and double displacement reactions with examples. Write balanced chemical equations for: (i) Zinc + dilute sulfuric acid and (ii) Lead nitrate + Potassium iodide.
[5]
Section E
- 19.
Read the passage and answer the questions: 'The digestive system breaks down complex food materials into simple molecules that can be absorbed by the intestines. Carbohydrates are broken down into glucose, proteins into amino acids, and fats into glycerol and fatty acids. The enzyme amylase acts on starch, pepsin acts on proteins in the stomach, and lipase acts on fats. Different enzymes work at different pH levels and temperatures. The small intestine is the main site of nutrient absorption.' (i) Name two enzymes mentioned and the nutrients they act upon. (1 mark) (ii) Why are different enzymes needed for different nutrients? (1 mark) (iii) What would happen if the small intestine lining was damaged? (1 mark) (iv) Name one hormone that regulates the movement of food through the digestive tract. (1 mark)
[4] - 20.
Read the case study and answer the questions: 'Mrs. Sharma's 12-year-old daughter has started showing signs of puberty — growth spurt, breast development, and menstruation. Mrs. Sharma is concerned about irregular menstrual cycles in the first two years. A doctor explained that this is normal and controlled by hormones. FSH and LH trigger menstruation, while estrogen and progesterone maintain the uterine lining.' (i) Name the gland that secretes FSH and LH. (1 mark) (ii) Define menstruation. Why does it occur? (1.5 marks) (iii) Why are menstrual cycles often irregular during adolescence? (1.5 marks)
[4]