111.

Energy is being emitted from the surface of a black body at 127°C the rate of 1.0 x 10⁶ J/sm². The temperature of the black body at which the rate of energy emission is 16.0 x 10° J/sm² will be

• 754⁰C

• 527⁰C

• 254⁰C

• 508⁰C

A body of specific heat 0.2 kcal/ kg° C is heated through 100°C. The percentage increase in its mass is

• 9%

• 9.3×10^-11 %

• 10%

• None of these

A raft of wood of mass 120 kg floats in water. The weight that can be put on the raft to make it just sink, should be (d _raft = 600 kg/m³)

• 80 kg

• 50 kg

• 60 kg

• 30 kg

A monoatomic gas supplied the heat Q very slowly keeping the pressure constant. The work done by the gas will be

• $\frac{2}{3}\mathrm{Q}$

• $\frac{3}{5 }\mathrm{Q}$

• $\frac{2}{5}\mathrm{Q}$

• $\frac{1}{5}\mathrm{Q}$

A perfect gas is found to obey the relation PV^3/2 = constant during an adiabatic process. If such a gas initially at a temperature T, is compressed to half of its initial volume, then its final temperature will be :

• 2 T

• 4T

• (2)^1/2 T

• 2 (2)^1/2 T

In isothermal process, which of the following is not true?

• Temperature remains constant

• Internal energy does not change

• No heat enters or leaves the system

• none of the above

Which of the following processes is reversible?

• Transfer of heat by radiation

• Electrical heating of a nichrome wire

• Transfer of heat by conduction

• Isothermal compression

An ideal gas heat engine operates in Carnot cycle between 227^o C and 127^o C. It absorbs 6 × 10⁴ cal of heat at higher temperature. Amount of heat converted to work is

• 2.4 × 10⁴ cal

• 6 × 10⁴ cal 

• 1.2  × 10⁴

• 4.8  × 10⁴ cal

Which of the following parameters does not characterise the thermodynamic state of matter?

• Temperature

• Pressure

• Work

• Volume

The work of 146 kJ is performed in order to compress one kilo mole of a gas adiabatically and in this process the temperature of the gas increases by 7°C. The gas is (R= 8.3J mol^-1 K^-1 )

• diatomic

• triatomic

• a mixture of monoatomic and diatomic

• monoatomic