NEET UG 2014 — Thermodynamics

Steam at ${100 }^{o}C$ is passed into $20 g$ of water at ${10 }^{o}C.$ When water acquires a temperature of ${80}^{o}C,$ the mass of water present will be: [Take specific heat of water $=1 cal {g}^{-1 o}{C}^{-1}$ and latent heat of steam $=540 cal {g}^{-1}]$

The mean free path of molecules of a gas (radius ‘ $r$ ’) is inversely proportional to:

A thermodynamics system undergoes cyclic process $ABCDA$ as shown in Figure. The work done by the system in the cycle is: 

Certain quantity of water cools from ${70 }^{o}C$ to ${60 }^{o}C$ in the first $5$ minutes and to ${54 }^{o}C$ in the next $5$ minutes. The temperature of the surroundings is:

A monoatomic gas at a pressure $P,$ having a volume $V$ expands isothermally to a volume $2V$ and then adiabatically to a volume $16V.$ The final pressure of the gas is: (take $\gamma =5/3$)