Specific Heat Capacity and Quantity of Heat

1. 2kg of water is heated with a healing coil which draws 3.5A from a 200V mains for 2 minutes. What is the increase in temperature of the water? (a) 10°C (b) 15°C (c) 25 °C (d) 30°C [specific heat capacity of water – 4200Jkg-1K-1]
Right Choice: Option A

2. A 50W electric heater is used to heat a metal block of mass 5kg. If in 10minutes a temperature rise of 12°C is achieved, the specific heat capacity of the metal is (a) 400Jkg-1k-1 (b) 500 Jkg-1k-1 (c) 390 Jkg-1k-1 (d) 130 Jkg-1k-1
Right Choice: Option B

3. Thermal equilibrium between two objects exists when (a) the heat capacities of both objects are the same (b) one object losses heat continuously to the other (c) the temperatures of both objects are equal (d) the quantity of heat in both objects is the same
Right Choice: Option C

4. A 2000W electric heater is used to heat a metal object of mass 5kg initially at 10°C. If a temperature rise of 30°C is obtained after 10 mins, the heat capacity of the material is (a) 1.2 x 104J°C-1 (b) 6.0 x 104J°C-1 (c) 8.0 x 104J°C-1 (d) 4.0 x 104J°C-1
Right Choice: Option B

5. How long does it take a 750W heater to raise the temperature of 1 kg of water from 20°C to 50°C? (Specific heat capacity of water = 4200Jkg-1k-1 (a) 84 s (b) 112s (c) 168s (d) 280 s
Right Choice: Option C

6. How much heat is absorbed when a block of copper of mass 0.05 kg and specific heat capacity 390 Jkg-1 K-1 is heated from 20°C to 70°C? (a) 3.98 x 10-1J (b) 9.75 x 10-1J (c) 3.98 x 10-1J (d) 9.75 x 10-1J
Right Choice: Option D

7. 200g of water at.90°C is mixed with 100 g ofwater at 30°C. What is the final temperature? (a) 50°C (b) 60°C (c) 70°C (d) 80°C
Right Choice: Option C

8. When 100g of liquid L, at 78°C was mixed with Xg of liquid L3 at 50°C, the final temperature was 66°C. Given that the specific heat capacity of L2 is half that of L, find X (a) 50g (b) 100g (c) 150g (d) 200g
Right Choice: Option C

9. A quantity of ice at -10°C is heated until the temperature of the heating vessel is 90°C. Which of the following constants is NOT required to determine the quantity of heat supplied to the vessel? (a) specific heat capacity of ice. (b) specific heat capacity of water (c) specific latent heat of fusion (d) Specific latent heat of vapourization
Right Choice: Option D

10. An electric kettle with negligible heat capacity is, rated at 2 000W. If 2.0kg of water is put in it, how long will it take the temperature of water to rise from 20°C to 100°C? (a) 420s (b) 336s (c) 168s (d) 84s [heat capacity of water = 4200 Jkg-1K-1]
Right Choice: Option B

EXERCISE

105. Amass of a liquid at 30°C is mixed with a mass of the same liquid at 70°C and the temperature of the mixture is 45°C. Find the ratio of the mass of the cold liquid to the mass of the other liquid. (a) 3:5 (b) 5:3 (c) 3:7 (d) 7:3

106. Equal masses of copper and rubber are raised to the same temperature. After sometime, the copper was observed to be at a lower temperature because (a) the specific heat capacity of copper is lower than that of rubber (b) copper expands more than rubber (c) the specific heat capacity of rubber is lower than that of copper (d) rubber expands more than copper

107. A 500W heater is used to heat 0.6kg of water from 25°C to 100°C in t1 seconds. If another 1000W heater is used to heat 0.2kg of water from 10°C to 100°C in t2 seconds, find t1/t2, (a) 50 (b) 5 (c) 5/4 (d) 1/5

108. A piece of substance of specific heat capacity 450Jkg- K-1 falls through a vertical distance of 20m from rest. Calculate the rise in temperature of the substance on hitting the ground when all its energies are converted into heat. (a) 2°C/9(b) 4°C/9 (c) 9°C/4 (d) 9°C/2

109. The time rate of loss of heat by a body is proportional to the (a) temperature of its surrounding (b) temperature of the body (c) difference in temperature between the body and its surroundings (d) ratio of the temperature of the body to that of its surroundings

110. A good calorimeter should be of (a) low specific heat capacity and low heal conductivity (b) low specific heat capacity and high heal conductivity (c) high specific heat capacity and low heal conductivity (d) high specific heat capacity and low heal conductivity

Facebook Comments
Posted in Lecture Notes.