A hydrometer is an instrument for measuring the

• A. a depth of water of water in a vessel
• B. relative density of a liquid by the method of flotation
• C. relative density of a liquid by finding the apparent loss in weight
• D. relative humidity of the air

The real image of an object formed by a converging lens of focal length 15cm, is three times the size of the object. Calculate the object distance

• A. 60cm
• B. 30cm
• C. 20cm
• D. 15cm

(a) Define the boiling point of a liquid.

(b) Describe an experiment to determine the boiling point of small quantity of a liquid.

(c) A piece of copper of mass 300 g at a temperature of 950°C is quickly transferred to a vessel of negligible thermal capacity containing 250 g of water at 25°C. If the final steady temperature of the mixture is 100°C, calculate the mass of the water that will boil away.

[Specific heat capacity of copper = \(4.0 \times 10^{2} Jkg^{-1} K^{-1}\); Specific heat capacity of water = \(4.2 \times 10^{3} Jkg^{-1} K^{-1}\); Specific latent heat of vaporization of steam = \(2.26 \times 10^{6} Jkg^{-1}\)

(d) State four other effects of heat on a substance other than expansion.

The electromagnetic wave that can produce a heating effect on the environment is

• A. x -rays
• B. ultraviolet rays
• C. infrared rays
• D. gamma rays

During electrolysis, 2.0 g of a metal is deposited using a current of 0.5 A in 3 hours. The mass of the same metal which can be deposited using a current of 1.5 A in 1 hour is?

• A) 1.0 g
• B) 0.5 g
• C) 3.0 g
• D) 2.0 g

A 0 - 10mA galvanometer with a coil resistance of 30\(\Omega\) can be converted to a 0 - 10A ammeter by using

• A. 0.03\(\Omega\) series resistor
• B. 0.03\(\Omega\) shunt resistor
• C. 9.99\(\Omega\) shunt resistor
• D. 9.99\(\Omega\) series resistor

At what angle to the horizontal must the nozzle of a machine gun be kept when firing to obtain a maximum horizontal range for the bullets?

• A. 0.0°
• B. 22.5°
• C. 30.0°
• D. 45. 0°

(a)(i) Mention two modes of heat transfer other than convection.

(ii) Explain land and sea breezes.

(b) An iron rod of length 30cm is heated through 50 kelvin. Calculate its increase in length. (linear expansivity of iron = 1.2 x 10\(^{-5}\)K\(^{-1}\)

(c) An electric heater immersed in some water raises the temperature of the water from 40°C to 100°C in 6 minutes. After another 25 minutes, it is noticed that half the water has boiled away. Neglecting heat losses to the surrounding, calculate the specific latent heat of vaporisation of water.

Which of the following graphs gives the correct relationship between energy and mass when mass is converted to energy.

• A. A
• B. B
• C. C
• D. D

If a plastic sphere floats in water (density = 1000kgm³) with 0.5 of its volume submerged, and floats in oil with 0.4 of its volume submerged the density of the oil is

• A. 800kgm³
• B. 1200kgm³
• C. 1250kgm³
• D. 2000kgm³