Question

A triatomic, diatomic and monatomic gas is supplied same amount of heat at constant pressure, then

• A. Fractional energy used to change internal energy is maximum in monatomic gas
• B. Fractional energy used to change internal energy is maximum in diatomic gas
• C. Fractional energy used to change internal energy is maximum in triatomic gases
• D. Fractional energy used to change internal energy is same in all the three gases

Answer 1

Answer: (C)

$\frac{\Delta U}{\Delta Q}=\frac{n{C}_V\Delta T}{n{C}_P\Delta T}=\frac{C_V}{C_P}=\frac{1}{\gamma }$
${\left(\frac{\Delta U}{\Delta Q}\right)}_{\text{mono }}=\frac{1}{{\gamma }_{\text{mono }}}=\frac{3}{5}$
${\left(\frac{\Delta U}{\Delta Q}\right)}_{\text{dia }}=\frac{1}{{\gamma }_{\text{dia }}}=\frac{5}{7}$
${\left(\frac{\Delta U}{\Delta Q}\right)}_{\text{tria }}=\frac{1}{{\gamma }_{\text{tria }}}=\frac{3}{4}$
Fractional energy used to change internal energy is maximum in Triatomic gas.