The $\Delta E^o$ of combustion of $2-$methylpropene is $-X \ kJ \ mol^{-1}$. The value of $\Delta H^o$ is

For the reaction
$A_{(\ell)} \rightarrow 2 B_{(g)}$
$\Delta U = 2.1 \; kcal, \Delta S = 20 \; cal \; K^{-1} \; mol^{-1}$ at $300 \; K$
Hence $\Delta G$ in $kcal \; mol^{-1}$ is

The combustion of one mole of benzene takes place at $298 \, K$ and $1 \, atm$. After combustion,$CO_{2(g)}$ and $H_2O_{(l)}$ are produced and $3267.0 \, kJ$ of heat is liberated. Calculate the standard enthalpy of formation,$\Delta_f H^{\ominus}$ of benzene. Standard enthalpies of formation of $CO_{2(g)}$ and $H_2O_{(l)}$ are $-393.5 \, kJ \, mol^{-1}$ and $-285.83 \, kJ \, mol^{-1}$ respectively.

An electric heater of power $600 \, W$ takes $8 \, \text{minutes}$ to evaporate $80 \, mL$ of water. The enthalpy of vaporization of water is ......... $kJ \, mol^{-1}$.

$A$ sample of $n$-octane $(1.14 \ g)$ was completely burnt in excess of oxygen in a bomb calorimeter,whose heat capacity is $5 \ kJ \ K^{-1}$. As a result of the combustion reaction,the temperature of the calorimeter increased by $5 \ K$. The magnitude of the heat of combustion of octane at constant volume is $.......... \ kJ \ mol^{-1}$ (nearest integer).

For the reaction $2Cl_{(s)} \to Cl_{2(s)}$,the signs of $\Delta H$ and $\Delta S$ respectively are