Comprehension-1
Two closed identical conducting containers are found in the laboratory of an old scientist. For the vertification of the gas some experiments are performed on the two boxes and the results are noted.

Experimenet 1.
When the two containers are weighed `W_(A) = 225tg, W_(B) = 160 g` and mass of evacuated container `W_(C) = 100g`.
Experiment 2.
When the two containers are given same amount of heat same temperature rise is recorded. The pressure changes found are
`DeltaP_(A) = 2.5 atm, Deltap_(B) = 1.5 atm`.
Required data for unknown gas:
`|(underset("molar mass")(Mono)",He,Ne,Ar,Kr,Xe,Rd),(,4g,20g,40g,84g,131g,222g),(underset(molar mass)(Dia),H_(2),F_(2),N_(2),O_(2),CI_(2),),(,2g,19g,28g,32g,71g,)|`
The initial internal energy of the gas in container 'A'. If the container were at room temperature initially

Options

A. `1406.25 "cal"`
B. `1000"cal"`
C. `2812.5 "cal"`
D. None of these

Answer

C

Explanation

`U = nC_(V)T = (125)/(40) xx (3)/(2) xx 2 xx 300 = 2812.5 "cal"`