If the door of a refrigerator is kept open, then which of the following is true ?

1. Room is cooled

2. Room is heated

3. Room is either cooled or heated

4. Room is neither cooled nor heated

A Carnot's engine used first an ideal monoatomic gas then an ideal diatomic gas. If the source and sink temperature are 411°C and 69°C respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the PV diagram is -

(1) 100 J

(2) 300 J

(3) 500 J

(4) 700 J

The temperature of reservoir of Carnot's engine operating with an efficiency of 70% is 1000K. The temperature of its sink is -

(1) 300 K

(2) 400 K

(3) 500 K

(4) 700 K

Efficiency of a Carnot engine is 50% when temperature of outlet is 500 K. In order to increase efficiency up to 60% keeping temperature of intake the same what is temperature of outlet ?

(1) 200 K

(2) 400 K

(3) 600 K

(4) 800 K

An ideal heat engine working between temperatures T₁ and T₂ has an efficiency η. The new efficiency if both the source and sink temperatures are doubled will be:
1. $\frac{\eta }{2}$
2. η
3. 2η
4. 3η

An engine is supposed to operate between two reservoirs at temperature 727°C and 227°C. The maximum possible efficiency of such an engine is -

(1) 1/2

(2) 1/4

(3) 3/4

(4) 1

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

(1) 2.4 × 10⁴ cal

(2) 6 × 10⁴ cal

(3) 1.2 × 10⁴ cal

(4) 4.8 × 10⁴ cal

A monoatomic ideal gas, initially at temperature \(T_1\), is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature \(T_2\) by releasing the piston suddenly. If \(L_1\) and \(L_2\) are the lengths of the gas column before and after expansion, respectively, then \(\frac{T_1}{T_2}\) is given by:
1. \(\left(\frac{L_1}{L_2}\right)^{\frac{2}{3}}\)
2. \(\frac{L_1}{L_2}\)
3. \(\frac{L_2}{L_1}\)
4. \(\left(\frac{L_2}{L_1}\right)^{\frac{2}{3}}\)

An ideal gas expands isothermally from a volume V₁ to V₂ and then compressed to original volume V₁ adiabatically. Initial pressure is P₁ and final pressure is P₃. The total work done is W. Then -

(1) $P_3>P_1,W>0$

(2) $P_3<P_1,W<0$

(3) $P_3>P_1,W<0$

(4) $P_3=P_1,W=0$

An insulator container contains 4 moles of an ideal diatomic gas at a temperature T. If heat Q is supplied to this gas, due to which 2 moles of the gas are dissociated into atoms, but the temperature of the gas remains constant, then:
1. Q = 2RT
2. Q = RT
3. Q = 3RT
4. Q = 4RT