The molar heat capacity for an ideal gas at constant pressure is $20.785 \ J \ K^{-1} \ mol^{-1}$. The change in internal energy is $5000 \ J$ upon heating it from $300 \ K$ to $500 \ K$. The number of moles of the gas is [Nearest integer] (Given: $R = 8.314 \ J \ K^{-1} \ mol^{-1}$)

$A$ fish swimming in a water body,when taken out,is covered with a film of water of weight $36 \ g$. When it is subjected to cooking at $100^{\circ} C$,the internal energy change for vaporization in $kJ \ mol^{-1}$ is $......$ [nearest integer].
[Assume steam to be an ideal gas. Given $\Delta_{vap} H^{\ominus}$ for water at $373 \ K$ and $1 \ bar$ is $41.1 \ kJ \ mol^{-1}$; $R = 8.31 \ J \ K^{-1} \ mol^{-1}$]

The enthalpy of combustion of carbon monoxide at $17 ^\circ C$ and constant volume is $-283.3 \ kJ$. Calculate the enthalpy of combustion at constant pressure in $kJ$.

When $200 \ cm^3$ of $0.1 \ M \ H_2SO_4$ is mixed with $150 \ cm^3$ of $0.2 \ M \ KOH$,the heat produced is ..... $kJ$.

For the reaction $\frac{1}{2}X_2 + \frac{3}{2}Y_2 \to XY_3$,$\Delta H = -30 \ kJ/mol$. Given $\Delta S_{X_2} = 60 \ J/mol \cdot K$,$\Delta S_{Y_2} = 40 \ J/mol \cdot K$,and $\Delta S_{XY_3} = 50 \ J/mol \cdot K$,calculate the temperature at equilibrium in $K$.

Which of the following relations are correct?
$(A)$ $\Delta U = q + p \Delta V$
$(B)$ $\Delta G = \Delta H - T \Delta S$
$(C)$ $\Delta S = \frac{q_{rev}}{T}$
$(D)$ $\Delta H = \Delta U - \Delta nRT$
Choose the most appropriate answer from the options given below: