Thermodynamics Questions

Assuming the sun to be a spherical body of radius $R$ at a temperature of $T\text{K}$, evaluate the total radiant power incident on Earth at a distance $r$ from the Sun. (where $r_0$ is the radius of the Earth and $\sigma$ is Stefan’s constant).

Work of $146\text{kJ}$ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by $7^{\circ }\text{C}$. The gas is: ($R=8.3{\text{J mol}}^{-1}{\text{K}}^{-1}$)

Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature $T_0$, while Box B contains one mole of helium at temperature $(7/3)T_0$. The boxes are put into thermal contact. The final temperature $T_f$ is:

An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If $T_i$ is the initial temperature and $T_f$ is the final temperature, which of the following statements is correct?

($\Delta H-\Delta U$) for the formation of carbon monoxide ($\text{CO}$) from its elements at $298\text{K}$ is ($R=8.314{\text{J K}}^{-1}{\text{ mol}}^{-1}$):