Thermal Energy

Q.

Name the S.I. unit of heat.

Q.

What is room temperature?

Q.

200 g of hot water at 80°C is added to 300 g of cold water at 10°C. Calculate the final temperature of the mixture of water. Consider the heat taken by the container to be negligible. The specific heat capacity of water is 4200 J kg^-1 °C^-1

1. 38^oC

2. 40^oC

3. 20^oC

4. 50^oC

Q.

A piece of ice of mass 40 g is dropped into 200 g of water at 50°C. Calculate the final temperature of water after all the ice has melted. Specific heat capacity of water = 4200 J/kg^oC , Specific latent heat of fusion of ice = 336 x 10³ J/kg.

1. 28.33^oC

2. 38.88^oC

3. 25.33^oC

4. 45.55^oC

Q.

With a neat diagram of a biogas plant write its construction and working?

Q.

A bubble of 5.00 mol of helium is submerged at a certain depth in liquid water when the water (and thus the helium) undergoes a temperature increase $\Delta T$ of ${20.0}^{\circ }C$; at constant pressure. As a result, the bubble expands. The helium is monoatomic and ideal. How much work W is done by the helium as it expands against the pressure of the surrounding water during the temperature increase? Use the first law of thermodynamics.​

1. 820 J

2. 831 J

3. 883 J

4. 805 J

Q.

Water falls from a height of 50 m. Calculate the rise in temperature of water when it strikes the bottom. Take g = 10 m s^-2 and specific heat capacity of water = 4200 J kg^-1 °C^-1).

1. 1200°C

2. 0.12°C

3. 4200°C

4. 4.2°C

Q.

__ is the study of the production of very low temperature (below 123K) and the behavior of materials at those temperatures.

Q.

State True or False:

Heat is the direction of heat or energy flow.

1. True

2. False

Q.

Specific heat capacity of water is 4.2 J/g⁰C & Specific heat capacity of mercury is 0.42 J/g⁰C. 4.2 J of heat is supplied to 1 g each of them. What will be the rise in temperature of each of them?

1. 10^oC rise for water, 1^oC rise for mercury

2. 10^oC rise for water, 3^oC rise for mercury

3. 5^oC rise for water, 10^oC rise for mercury

4. 12^oC rise for water, 1^oC rise for mercury

5. 1^oC rise for water, 10^oC rise for mercury

Q.

The temperature of the body is the average internal kinetic energy of molecules of a substance.

1. True

2. False

Q.

____________ is the practical unit of heat.

Q.

A hot and a cold body are kept in a vacuum separated from each other. Which of the following causes a decrease in the temperature of the hot body?

1. Radiation

2. Convection

3. Conduction

4. Temperature does not change

Q.

The amount of heat required to raise the temperature of 1g of water by 1°C is known as __________

1. latent heat

2. heat capacity

3. one calorie

4. one joule

Q.

What is/are the unit/units of heat?

1. Joule.

2. °C

3. Pascal

4. Calorie

Q.

The heat released by a copper ball of mass 1 kg when cooled from 100°C to 90°C is 8.4 kJ. Calculate the specific heat capacity of copper.

1. 840 kJ/kg°C

2. 840 J/kg°C

3. 84 J/kg°C

4. 840 J/g°C

Q.

What is the basic principle of thermopile?

Q.

Define calorie and kilocalorie.

Q. A wire of length $L_0$ is supplied heat to to raise its temperature by T. If $\gamma$ is the coefficient of volume ex the wire and Y is the young's modulus of the wire then the energy density stored in the wire is

1. 
2. 
3. 
4. 

Q.

3.75 x 10⁵ calories of heat is given out by 5 kg of water at 100 °C. Calculate the temperature of cooled water. The specific heat capacity of water is 1000 cal kg^-1 °C^-1.

Q. How much energy will it take for 0.5 kg water to rise from a temperature of 25℃ to 35℃?

1. 
   5 kcal
2. 
   10 kcal
3. 
   20 kcal
4. 
   2.5 kcal

Q. If you constantly strike an iron bar with a hammer, the temperature of the bar .

1. decreases
2. does not change
3. increases
4. is not measurable

Q.

How does thermal radiation change with temperature?

Q. A window air conditioner is brought into the center of a dorm room and turned on. After several minutes, the temperature of the room:

1. increases

2. decreases

3. remains constant

4. depends on the brand of the AC

Q.

what is the unit of water equivalent

Q.

Choose the correct statement(s) among the following

1. The work done in an isochoric process is a function of the temperature only

2. > for all gases, without exception

3. The work done by a gas in an isobaric process is responsible for different values of and

Q.

Units of energy other than its S.I units & its multiples are:

1. KJ, erg, dyne, calories

2. dyne, calories, newton, erg

3. calories, watt, erg, eV

4. calories, kWh, erg, eV

5. calories, kWh, erg, dyne

Q.

Calculate the heat capacity of a substance which requires 4000 J of heat to raise its temperature by 20⁰C. Also calculate the SHC of the substance if its mass is 100 g.

1. i) 200 J⁰ C^-1 ii) 2 J g^{-1 0}C^-1

2. i) 20 J⁰ C^-1 ii) 2 J g^{-1 0}C^-1

3. i) 20000 J⁰ C^-1 ii) 200 J g^{-1 0}C^-1

4. i) 200 J⁰ C^-1 ii) 2 J g^{-1 0}C^-1

5. i) 0.2 J⁰ C^-1 ii) 20 J g^{-1 0}C^-1

Q.

Define heat with measurement unit.

Q. 2 L of an ideal gas at a pressure of 10 atm expand isothermally into a vaccum until its total volume is 10 L.
(i) How much heat is absorbed and how much work is done in the expansion?
(ii) How much heat is absorbed if this system expands against a constant external pressure of 1 arm?
(iii) How much heat is absorbed if the expansion is conducted reversibly at 298 K.