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

The efficiency of an ideal heat engine is less than 100% because of:

A heat engine operates between the temperatures of 300 K and 500 K. If it extracts 1200 J of heat energy from the source, then the maximum amount of work that can be done by the engine is:

1. 720 J

2. 520 J

3. 480 J

4. 200 J

The efficiency of a Carnot heat engine working between the temperatures \(27^{\circ}\mathrm{C}\)$$ and \(227^{\circ}\mathrm{C}\) is:
1. 0.1
2. 0.6
3. 0.2
4. 0.4

The efficiency of an ideal heat engine (Carnot heat engine) working between the freezing point and boiling point of water is:
1. \(26.8\%\)
2. \(20\%\)
3. \(6.25\%\)
4. \(12.5\%\)

An ideal gas heat engine operates in a Carnot cycle between 227ºC and 127ºC. It absorbs 6 × 10⁴ cals of heat at higher temperatures. The amount of heat converted to work will be?
1. 4.8 × 10⁴ cals
2. 2.4 × 10⁴ cals
3. 1.2 × 10⁴ cals
4. 6 × 10⁴ cals

A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by \(62^{\circ}\mathrm{C}\), the efficiency of the engine is doubled. The temperatures of the source and sink are: 
1. \(80^{\circ}\mathrm{C}, 37^{\circ}\mathrm{C}\)
2. \(95^{\circ}\mathrm{C}, 28^{\circ}\mathrm{C}\)
3. \(90^{\circ}\mathrm{C}, 37^{\circ}\mathrm{C}\)
4. \(99^{\circ}\mathrm{C}, 37^{\circ}\mathrm{C}\)

If the temperature of the source and the sink in the heat engine is at 1000 K & 500 K respectively, then the efficiency can be:
1. 20%
2. 30%
3. 50%
4. All of these

A heat engine is working between 200 K and 400 K. The efficiency of the heat engine may be:

1. 20%

2. 40%

3. 50%

4. All of these

In a Carnot engine, when \(T_2=0^\circ \mathrm{C}\) and \(T_1=200^\circ \mathrm{C},\) its efficiency is \(\eta_1\) and when \(T_1=0^\circ \mathrm{C}\) and \(T_2=-200^\circ \mathrm{C},\) its efficiency is \(\eta_2.\) What is the value of \(\frac{\eta_1}{\eta_2}?\)