Question

A cylinder of fixed capacity `44.8` litres constains helium gas at standard temperature and pressure. What is the amount of heat needed to raise the temperature of the gas in the cylinder by `15^(@)C` ? Given `R=8.31 j mol e^(-1) K^(-1)` . (For monoatomic gas, `C_(v)=3 R//2`)
A. 265 J
B. `310.10 J`
C. `373.95 J`
D. `387.97 J`

Answer 1

Correct Answer - C
Since one mole of any ideal gas at STP occupies a volume of 22.4 litre.
Therefore, cylinder of fixed capacity 44.8 litre must contain 2 moles of helium at STP.
For helium, `C_(V)=3/2R` (monatomic)
`therefore` Heat needed to raise the temperature,
Q= number of moles `xx` molar specific heat `xx` raise in temperature
`=2xx3/2Rxx15=45R=45xx8.31J=373.95J`