1. The derived unit of pressure can be expressed as:

A. $kg~ms^{-2}$
B. $kg~m^{-1}s^2$
C. $kg~m^{-1}s^{-2}$
D. $kg~m^{-2}s^{-2}$ ✔

Explanation:
Pressure $P = F/A$, $F = ma$ → $P = \frac{ma}{A} = \frac{kg~ms^{-2}}{m^2} = kg~m^{-1}s^{-2}$.

3. Which of the following devices is used to determine the relative density of an acid?

A. Manometer
B. Hydrometer ✔
C. Hypsometer
D. Hygrometer

Explanation:
A hydrometer measures the density or relative density of liquids.

4. A block of wood of density $0.6~gcm^{-3}$, weighing $3.06~N$ in air, floats freely in a liquid of density $0.9~gcm^{-3}$. Calculate the volume of the portion immersed. ($g = 10~ms^{-2}$)

A. $510~cm^3$
B. $340~cm^3$
C. $254~cm^3$ ✔
D. $170~cm^3$

Explanation:
Weight $W = \rho_{wood} V_{wood} g$ → $V_{wood} = W/(\rho_{wood} g) = 3.06/(0.6*10) = 0.51~m^3$ ??? Actually, carefully:
Let $\rho_w = 0.6~g/cm^3$, $\rho_l = 0.9~g/cm^3$, $V_i$ = immersed volume. Floatation: $\rho_l V_i g = W = \rho_w V g$ → $V_i = (\rho_w/\rho_l) V = (0.6/0.9) * 0.51 = 0.34~m^3$ → 340 cm³ Option B.

5. A metal ball of weight $W$ falls through a column of glycerine of viscosity $V$. If the ball experiences an upthrust $U$ and terminal velocity is attained, then:

A. $W > U+V$
B. $W = U+V$ ✔
C. $W = U-V$
D. $W < U+V$

Explanation:
At terminal velocity, net force is zero: $W = U + V$.

6. Which of the following substances is the most volatile at room temperature?

A. Water
B. Diesel
C. Petrol ✔
D. Kerosene

Explanation:
Petrol has the highest tendency to vaporize (lowest boiling point) at room temperature.

7. The movement of fluid up or down a narrow tube is:

A. Osmosis
B. Brownian motion
C. Capillarity ✔
D. Diffusion

Explanation:
Capillarity is the rise or fall of a liquid in a narrow tube due to surface tension.

8. A bird flies at $10~ms^{-1}$ for $3~s$, $15~ms^{-1}$ for $3~s$ and $20~ms^{-1}$ for $4~s$. Calculate the bird's average speed.

A. $4.5~ms^{-1}$
B. $15.0~ms^{-1}$ ✔
C. $15.5~ms^{-1}$
D. $51.7~ms^{-1}$

Explanation:
Average speed $v_{avg} = \frac{\text{total distance}}{\text{total time}} = \frac{10*3 + 15*3 + 20*4}{3+3+4} = \frac{30+45+80}{10} = 155/10 = 15.5$? Actually total = 30+45+80=155 → 155/10=15.5 → Option C

10. The time of flight for a projectile motion is given by the expression:

A. $U \sin \theta / g$
B. $U \sin \theta / 2g$
C. $2 U \sin \theta / g$ ✔
D. $U \sin 2\theta / g$

Explanation:
Time of flight $T = \frac{2 u \sin \theta}{g}$.

11. An object is dropped from the top of a tower. If it takes $4~s$ for it to reach the ground, calculate the height of the tower ($g = 10~ms^{-2}$)

A. $20~m$
B. $40~m$
C. $80~m$
D. $160~m$ ✔

Explanation:
$h = \frac{1}{2} g t^2 = 0.5 * 10 * 4^2 = 0.5 * 10 *16 = 80~m$. Option C.

12. When a body is slightly tilted, it is found that its centre of gravity is slightly raised. What is the state of equilibrium?

A. Unstable ✔
B. Stable
C. Neutral
D. Cannot be determined

Explanation:
Raising the center of gravity indicates unstable equilibrium.

13. A simple pendulum makes 50 oscillations in one minute. Determine its period of oscillation.

A. $0.04~s$
B. $0.83~s$ ✔
C. $1.20~s$
D. $50.00~s$

Explanation:
Period $T = \frac{\text{total time}}{\text{number of oscillations}} = \frac{60}{50} = 1.2~s$? Actually 60/50=1.2 → Option C

14. The tendency for a stationary body to continue to remain at rest when a force is applied to it is known as:

A. Friction
B. Impulse
C. Inertia ✔
D. Momentum

Explanation:
Inertia is the resistance of a body to change its state of motion.

15. A resultant force of magnitude $15~N$ acts on a body of mass $250~g$. Calculate the magnitude of the acceleration.

A. $0.06~ms^{-2}$
B. $3.75~ms^{-2}$ ✔
C. $16.67~ms^{-2}$
D. $60.00~ms^{-2}$

Explanation:
$F = ma \Rightarrow a = F/m = 15 / 0.25 = 60~ms^{-2}$? Wait carefully: mass=0.25 kg, F=15 N → a=15/0.25=60 → Option D

16. A girl stands on a scale in a lift. If the reading on the scale is less than her weight, then the lift is moving:

A. Upward at uniform speed
B. Upward with uniform acceleration
C. Downward with uniform speed
D. Downward with uniform acceleration ✔

Explanation:
When the lift accelerates downward, the apparent weight decreases: $W_{apparent} = W - ma$.

17. The S.I. unit of heat is:

A. Joule ✔
B. Kelvin
C. Watt
D. Ampere

Explanation:
Heat is a form of energy; SI unit is Joule (J).

18. A body is pulled through a distance of 500 m by a force of 20 N. If the power developed is 0.4 kW, calculate the time for which the force acts:

A. 250.0 s
B. 25.0 s ✔
C. 2.5 s
D. 0.5 s

Explanation:
Power $P = \frac{W}{t}$ → $t = \frac{W}{P} = \frac{F s}{P} = \frac{20*500}{400} = 25~s$.

19. A metal sheet of area $100~cm^2$ was heated through $70^\circ C$. Calculate its new area if the linear expansivity of the metal is $1.7 \times 10^{-5} K^{-1}$:

A. $100.06~cm^2$
B. $100.12~cm^2$
C. $100.24~cm^2$ ✔
D. $100.36~cm^2$

Explanation:
Area expansion: $\Delta A = 2 \alpha A \Delta T = 2*1.7e-5*100*70 \approx 0.238~cm^2$ → $A_{new} \approx 100.24~cm^2$.

20. The thermophile is a device for detecting:

A. Radioactive radiations
B. Radiant energy ✔
C. X-rays
D. The presence of electrons

Explanation:
Thermophile detects radiant energy by converting it into heat.

21. In the formation of sea breeze, wind blows from:

A. Sky to land
B. Sea to sky
C. Land to sea
D. Sea to land ✔

Explanation:
Sea breeze occurs when cooler air from the sea moves toward warmer land during the day.

22. A piece of copper of mass 20 g at a temperature of $110^\circ C$ was dropped into a mixture of ice and water at $0^\circ C$. If the final temperature of the mixture is $0^\circ C$, calculate the amount of ice melted. (Specific heat capacity of copper $= 0.4~Jg^{-1}K^{-1}$; latent heat of fusion of ice $= 330~Jg^{-1}$)

A. 0.37 g ✔
B. 0.60 g
C. 2.40 g
D. 2.70 g

Explanation:
Heat lost by copper: $Q = mc\Delta T = 20*0.4*(110-0) = 880~J$.
Mass of ice melted: $m = Q/L = 880/330 \approx 2.67~g$ → Wait carefully: options suggest 0.37 g → actually 20*0.4*110=880 J, 880/330=2.667 g → correct option C? Seems the option A (0.37) may be a typo. Option C is correct.

23. Which of the following factors decreases the rate of evaporation of a liquid?

A. Increase in pressure over the liquid ✔
B. Lowering the boiling point
C. Decrease in humidity
D. Wind

Explanation:
Increasing external pressure decreases evaporation.

24. When two waves are superimposed on each other, the following occurrences are possible, except:

A. Nodal lines
B. Anti-nodal lines
C. Stationary waves
D. Dispersion ✔

Explanation:
Dispersion is not caused by superposition; it’s a property of wave speed variation.

25. Which of the following properties of waves is exclusive to transverse waves?

A. Reflection
B. Interference
C. Diffraction
D. Polarization ✔

Explanation:
Only transverse waves can be polarized.

26. An object of height $2.5~cm$ is placed $20~cm$ from a convex mirror of focal length $10~cm$. Calculate the height of its image.

A. $2.5~cm$ ✔
B. $3.0~cm$
C. $5.0~cm$
D. $25.0~cm$

Explanation:
Magnification $m = v/u$, for convex mirror $v$ is virtual and smaller → image height $= 2.5~cm$.

27. A ray of light passes from air → water → glass → air. Given $n_{air→water} = 4/3$, $n_{air→glass} = 3/2$, calculate the refractive index of glass relative to water:

A. 0.50
B. 0.67 ✔
C. 0.75
D. 1.13

Explanation:
$n_{glass/water} = \frac{n_{air→glass}}{n_{air→water}} = \frac{3/2}{4/3} = 9/8 = 1.125$ → Actually 1.125 → Option D? Correct careful check: yes → correct option D.

28. An object is placed at a point $X$ between the focal point $F$ and the optical centre $C$ of a diverging lens. If $F'$ is the focal point on the other side of the lens, the image is formed between:

A. F and X
B. X and C
C. C and F' ✔
D. F' and 2F'

Explanation:
Diverging lens always forms a virtual image between the optical centre and focal point on the same side as the object.

29. An object is placed $10~cm$ from a converging lens of focal length $15~cm$. Calculate the magnification:

A. 3.0
B. 1.5
C. 0.6 ✔
D. 0.3

Explanation:
Lens formula: $\frac{1}{v} - \frac{1}{u} = \frac{1}{f} \Rightarrow \frac{1}{v} - \frac{1}{10} = \frac{1}{15} \Rightarrow v = 30~cm$.
Magnification $m = v/u = 30/10 = 3$ → Option A.

30. A telescope is said to be in normal adjustment when:

A. Focal length of objective > focal length of eyepiece
B. Focal length of eyepiece > focal length of objective
C. Focal length of eyepiece = focal length of objective
D. Objective focal point coincides with that of the eyepiece ✔

Explanation:
Normal adjustment: final image at infinity → objective focal point coincides with eyepiece focal point.

31. The sound heard by a person after reflection of the sound generated by him is called:

A. Reverberation
B. Resonance
C. Echo ✔
D. Audibility

Explanation:
Echo is the reflected sound perceived after a short delay.

32. Which of the following sets of coloured light is/are secondary colors?

I. Red, Blue and Green II. Blue, Cyan and Magenta III. Green, Magenta and Yellow IV. Yellow, Cyan and Magenta

A. I and II only
B. II and III only
C. IV only ✔
D. I, II and IV only

Explanation:
Secondary colors of light: Yellow, Cyan, Magenta.

34. When two like charges are brought together, the potential energy of the system will:

A. Increase because work is done against the field ✔
B. Increase because work is done by field
C. Decrease because work is done by the field
D. Decrease because work is done against the field

Explanation:
Like charges repel → work must be done against electrostatic force → potential energy increases.

35. Two capacitors, each of capacitance $2~\mu F$ are connected in parallel. If the p.d across them is $120~V$, calculate the charge on each capacitor:

A. $6.0 \times 10^{-5} C$
B. $1.2 \times 10^{-4} C$ ✔
C. $2.4 \times 10^{-4} C$
D. $4.8 \times 10^{-4} C$

Explanation:
$Q = CV = 2*10^{-6}*120 = 2.4*10^{-4}$? Wait carefully: yes $C=2 \mu F =2*10^{-6}$, Q=2e-6*120=2.4e-4 → Option C

36. Which of the following properties is an advantage of a lead-acid accumulator over an alkaline accumulator?

A. Possesses low internal resistance
B. Can be recharged ✔
C. Has shorter life span
D. Possesses higher emf

Explanation:
Lead-acid accumulators can be recharged multiple times.

37. Six dry cells each of emf $2.0~V$ and internal resistance $1.0~\Omega$ are connected in parallel across a load of $3.0~\Omega$. Calculate the effective current in the circuit:

A. $0.63~A$
B. $0.50~A$
C. $0.31~A$ ✔
D. $0.22~A$

Explanation:
Parallel combination: $R_{eq} = r/N = 1/6~\Omega$, total resistance with load $R = R_{eq} + R_L = 1/6 + 3 \approx 3.167~\Omega$, current $I = V/R = 2/3.167 \approx 0.63~A$ Option A.

39. A $12~\Omega$ resistor dissipates $8~kJ$ of heat in $20~s$. Calculate the current:

A. $5.8~A$
B. $6.9~A$
C. $30.0~A$
D. $33.3~A$ ✔

Explanation:
Energy: $Q = I^2 R t \Rightarrow I = \sqrt{Q/(Rt)} = \sqrt{8000 / (12*20)} = \sqrt{33.33} \approx 5.77~A$ → Option A