Heat & Thermodynamics · JEE Main previous year questions

2018 3 questions

1. Q372018 · 15 Apr 2018 · Shift 1

   One mole of an ideal monoatomic gas is compressed isothermally in a rigid vessel to double its pressure at room temperature, $27^{\circ }C$. The work done on the gas will be :

   1. A.$300R$
   2. B.$300R\ln 6$
   3. C.$300R\ln 2$
   4. D.$300R\ln 7$
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   Answer: C

2. Q572018 · 15 Apr 2018 · Shift 1

   A Carnot's engine works as a refrigerator between 250 K and 300 K. It receives 500 cal heat from the reservoir at the lower temperature. The amount of work done in each cycle to operate the refrigerator is :

   1. A.$420J$
   2. B.$772J$
   3. C.$2100J$
   4. D.$2520J$
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   Answer: A

3. Q402018 · 8 Apr 2018 · Shift 1

   Two moles of an ideal monatomic gas occupies a volume V at $27^{\circ }\mathrm{C}$. The gas expands adiabatically to a volume 2 V. Calculate (a) the final temperature of the gas and (b) change in its internal energy.

   1. A.(a) 195 K (b) 2.7 kJ
   2. B.(a) 189 K (b) 2.7 kJ
   3. C.(a) 195 K (b) $-2.7\mathrm{kJ}$
   4. D.(a) 189 K (b) $-2.7\mathrm{kJ}$
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   Answer: D