Among the following,the number of state variables is $.....$
Internal energy $(U)$; Volume $(V)$; Heat $(q)$; Enthalpy $(H)$

The heat of combustion of benzene determined in a bomb calorimeter is $-870 \ kcal \ mol^{-1}$ at $25 \ ^oC$. The value of $\Delta E$ for the reaction is......$kcal$.

If in a container neither mass nor heat exchange occurs,then it constitutes a

If $5 \ L$ of an ideal gas at a constant external pressure of $2 \ atm$ expands isothermally to a final volume of '$X$' $L$,the system does a work of $-2,026.4 \ J$. '$X$' (in $L$) is $(1 \ L \cdot atm = 101.32 \ J)$

Calculate the constant external pressure required to expand $2$ moles of an ideal gas from volume $15 \ dm^{3}$ to $20 \ dm^{3}$ if the amount of work done is $-600 \ J$. (in $bar$)

If a chemical reaction is accompanied by the evolution of heat,it is