Question

For an ideal gas

• A. the change in internal energy in a constant pressure process from temperature $T_1$, to $T_2$ is equal to $nC_v (T_2-T_1)$, where C$_v$ is the molar heat capacity at constant volume and n the number of moles of the gas
• B. the change in internal energy of the gas and the work done by the gas are equal in magnitude in an adiabatic process
• C. the internal energy does not change in an isothermal process
• D. no heat is added or removed in an adiabatic process

Answer 1

Answer: (D)

no heat is added or removed in an adiabatic process

Answer 2

$\Delta U$ = nC$_v$ $\Delta$T = nC$_v$ (T$_2-t_1)$ in all processes

$\therefore \, \, \, \, \, \, \, \Delta$U = $-\Delta$W or | $\Delta$ U| = | $\Delta$ W |
(c) In isothermal process $\Delta$T = 0
$\therefore \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \Delta$U= 0 $\, \, \, \, \, \, \, \, \, \, \, (as \Delta U =nC_v \Delta T )$
(d) In adiabatic process $\Delta$Q = 0
$\therefore \, \,$ All the options are correct.