Question

If work done by a gas is $142.8J$ when heat given to the gas in isobaric process is $500J$, then the gas is

• A. $O_2$
• B. $N{H}_3$
• C. $He$
• D. $S{O}_2$

Answer 1

Answer: (A)

$W=P\left(V_2-V_1\right)=nR{T}_2-nR{T}_1$
$T_2-T_1=\frac{W}{nR}$
$Q=n{C}_p\left(T_2-T_1\right)$
$500=n{C}_p\frac{W}{nR}$
$500=\frac{C_{p}W}{R}$
$C_p=\frac{500R}{142.5}=3.5R=7/2R$
Hence, gas is diatomic $O_2$