The mathematical equation of the first law of thermodynamics for an isochoric process is:

The conservation of mass and energy is demonstrated by:

At $300 \ K$,the enthalpy change for the reaction $C_3H_8(g) + 5O_2(g) \rightarrow 3CO_2(g) + 4H_2O(l)$ is $-2800 \ kJ \ mol^{-1}$. Calculate the internal energy change $(\Delta U)$ for the reaction at the same temperature.

$A$ gas absorbs $200 \ J$ of heat and expands by $500 \ cm^3$ against a constant external pressure of $2 \times 10^5 \ N \ m^{-2}$. What is the change in internal energy (in $J$)?

For the gaseous reaction involving the complete combustion of isobutane,which of the following relations holds true?

The reaction in which $\Delta H > \Delta U$ is