Class 10 Board Examination — Physical Science Mock Test Paper Time: 3 Hours | Maximum Marks: 60
General Instructions: 1. Section A contains MCQs (1 mark each) 2. Section B contains Short Answer questions (2 marks each) 3. All questions are compulsory 4. Draw neat diagrams wherever necessary
SECTION A — Multiple Choice Questions
(1 Mark Each | 10 × 1 = 10 Marks)
Q1. Which of the following is a physical change? (a) Burning of wood (b) Rusting of iron (c) Melting of ice (d) Digestion of food
Q2. The pH of a neutral solution is: (a) 0 (b) 7 (c) 14 (d) 1
Q3. The chemical formula of baking soda is: (a) Na₂CO₃ (b) NaOH (c) NaHCO₃ (d) NaCl
Q4. Which of the following metals is stored in kerosene? (a) Gold (b) Sodium (c) Iron (d) Copper
Q5. The atomic number of an element is 17. It belongs to which period in the Modern Periodic Table? (a) 2nd period (b) 3rd period (c) 4th period (d) 5th period
Q6. An electric bulb is rated 220V and 100W. Its resistance is: (a) 284 Ω (b) 384 Ω (c) 484 Ω (d) 584 Ω
Q7. The SI unit of magnetic flux is: (a) Tesla (b) Weber (c) Ampere (d) Volt
Q8. Which mirror is used as a rear-view mirror in vehicles? (a) Plane mirror (b) Concave mirror (c) Convex mirror (d) Parabolic mirror
Q9. A ray of light passes from air into glass. It will: (a) Bend away from the normal (b) Bend towards the normal (c) Go straight without bending (d) Reflect back
Q10. The image formed by a concave lens is always: (a) Real and inverted (b) Virtual and erect (c) Real and erect (d) Virtual and inverted
SECTION B — Short Answer Questions
(2 Marks Each | 15 × 2 = 30 Marks)
Q11. Differentiate between exothermic and endothermic reactions. Give one example of each.
Q12. What is a balanced chemical equation? Why should chemical equations be balanced?
Q13. Define acids and bases according to the Arrhenius concept. Give one example of each.
Q14. What happens when zinc reacts with dilute sulphuric acid? Write the balanced chemical equation.
Q15. State two properties of metals that make them useful in everyday life.
Q16. What is the Modern Periodic Law? How does atomic size vary along a period from left to right?
Q17. State Ohm's Law. Write its mathematical form and mention the conditions under which it is valid.
Q18. Three resistors of 2 Ω, 3 Ω, and 6 Ω are connected in parallel. Find the equivalent resistance.
Q19. State Fleming's Left Hand Rule. For what purpose is it used?
Q20. What is electromagnetic induction? State Faraday's law of electromagnetic induction.
Q21. Define the principal focus of a concave mirror. An object is placed at the centre of curvature of a concave mirror. Where will the image be formed? State any two characteristics of the image.
Q22. A concave mirror has a focal length of 15 cm. An object is placed 30 cm in front of it. Find the image distance using the mirror formula.
Q23. Define the power of a lens. A lens has a focal length of 25 cm. What is its power?
Q24. State two differences between AC and DC. Name one source of each.
Q25. Draw a neat ray diagram to show the refraction of light through a glass slab and label the following: incident ray, refracted ray, emergent ray, and angle of refraction.
ANSWERS
Section A — Answers
A1. (c) Melting of ice
A2. (b) 7
A3. (c) NaHCO₃
A4. (b) Sodium
A5. (b) 3rd period
A6. (c) 484 Ω (R = V²/P = 220×220/100 = 48400/100 = 484 Ω)
A7. (b) Weber
A8. (c) Convex mirror
A9. (b) Bend towards the normal
A10. (b) Virtual and erect
Section B — Answers
A11. Exothermic reaction: A reaction that releases heat energy to the surroundings. Example: Burning of natural gas — CH₄ + 2O₂ → CO₂ + 2H₂O + Heat
Endothermic reaction: A reaction that absorbs heat energy from the surroundings. Example: Decomposition of calcium carbonate — CaCO₃ → CaO + CO₂ (on heating)
A12. A balanced chemical equation has equal numbers of atoms of each element on both sides of the equation. Chemical equations must be balanced to satisfy the Law of Conservation of Mass, which states that matter can neither be created nor destroyed in a chemical reaction.
A13. Arrhenius Acid: A substance that dissociates in water to produce H⁺ ions. Example: HCl → H⁺ + Cl⁻
Arrhenius Base: A substance that dissociates in water to produce OH⁻ ions. Example: NaOH → Na⁺ + OH⁻
A14. Zinc reacts with dilute sulphuric acid to produce zinc sulphate and hydrogen gas. Zn + H₂SO₄ → ZnSO₄ + H₂↑
This is a displacement reaction. Hydrogen gas is evolved which produces a pop sound when a burning splinter is brought near it.
A15. Two useful properties of metals:
- Malleability — Metals can be beaten into thin sheets (e.g., aluminium foil used for food packaging).
- Good conductors of electricity — Metals allow electric current to pass through them easily (e.g., copper wires used in electrical circuits).
A16. Modern Periodic Law: Properties of elements are periodic functions of their atomic numbers.
Variation of atomic size along a period: Atomic size decreases from left to right across a period. This is because the nuclear charge increases while electrons are added to the same shell, pulling them closer to the nucleus.
A17. Ohm's Law: The current flowing through a conductor is directly proportional to the potential difference across its ends, provided the temperature and other physical conditions remain constant.
Mathematical form: V = IR where V = potential difference (V), I = current (A), R = resistance (Ω)
Condition: Temperature and physical state of the conductor must remain constant.
A18. For parallel combination: 1/Rₚ = 1/R₁ + 1/R₂ + 1/R₃ 1/Rₚ = 1/2 + 1/3 + 1/6 1/Rₚ = 3/6 + 2/6 + 1/6 1/Rₚ = 6/6 = 1 Rₚ = 1 Ω
A19. Fleming's Left Hand Rule: Stretch the thumb, index finger, and middle finger of the left hand mutually perpendicular to each other. If the index finger points in the direction of the magnetic field and the middle finger in the direction of the current, then the thumb points in the direction of the force (motion) on the conductor.
It is used to find the direction of force acting on a current-carrying conductor placed in a magnetic field. It is applied in electric motors.
A20. Electromagnetic Induction: The phenomenon of producing an induced current in a coil whenever the magnetic flux linked with it changes is called electromagnetic induction.
Faraday's Law: The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux linked with the circuit. EMF ∝ ΔΦ/Δt
A21. Principal Focus of a concave mirror: The point on the principal axis at which all rays parallel to the principal axis converge after reflection is called the principal focus.
When an object is placed at the centre of curvature (C): The image is formed at C itself (same position). Characteristics of the image:
- Real and inverted
- Same size as the object
A22. Given: f = −15 cm (concave mirror), u = −30 cm Using mirror formula: 1/f = 1/v + 1/u 1/−15 = 1/v + 1/−30 1/v = 1/−15 + 1/30 1/v = −2/30 + 1/30 1/v = −1/30 v = −30 cm
The image is formed 30 cm in front of the mirror (real and inverted, same size as object).
A23. Power of a lens: The reciprocal of the focal length of a lens expressed in metres is called its power. P = 1/f (in metres)
Given: f = 25 cm = 0.25 m P = 1/0.25 = +4 D (Dioptres)
The positive sign indicates it is a convex (converging) lens.
A24.
| AC | DC | |
|---|---|---|
| Direction | Changes direction periodically | Flows in one direction only |
| Frequency | Has frequency (50 Hz in India) | Frequency is zero |
| Source | AC generator / Power stations | Battery / Cell |
A25. Ray diagram for refraction through a glass slab:
- The incident ray hits the top surface of the glass slab at an angle (angle of incidence).
- At the first surface, the ray bends towards the normal (refracted ray inside the slab).
- At the second surface, the ray bends away from the normal and emerges (emergent ray).
- The emergent ray is parallel to the incident ray but laterally displaced.
Labels: Incident ray → Normal → Refracted ray (inside slab) → Emergent ray → Angle of refraction (r) → Lateral displacement
(Draw a rectangular glass slab with the above ray path for full marks)
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