True false of class 12

True and False

Five Year Papers

1. The pressure and volume formula of a gas undergoing an Adiabatic change is PV = constant.

2. The graph of pressure and volume of a certain mass of a gas at constant temperature is a hyperbola.

3. A free electron in an electric field moves from the higher potential to the lower potential.

4. Under no condition can be heat be transferred from a body at a low temperature to one at a higher temperature.

Important Numerical of FSC part 2 or class 12 or inter Class

Numericals

Section A

1. Find the efficiency of a carnot engine working between 100°C and 50°C.

2. Find the root mean square of a hydrogen molecle at 7°C. Take the mass of a hydrogen molecule to be 3.32 x 10-27 kgm and Boltzmann’s constant = 1.38 x 10-23 joules/°K.

3. 540 calories of heat is required to vapoirze 1 gm of water at 100°C. Define the entropy change involved in vaporizing 5gm of water. (1 calorie = 4.2 joules)

4. A glass flask is filled to the mark with 60cm3 of mercury at 20°C. If the flask and its contents are heated to 40°C, how much mercury will be above the mark? a for glass = 9 x 10-6 /°C and b for mercury = 182 x 10-6 /°C.

5. A carnot engine whose low temperature reservoir is 200°K has an efficiency of 50%. It is desired to increase this to 75%. By how many degrees must the temperature be decreased, if higher temperature of the reservoir remains constant?