$28.0 \, L$ of $CO_2$ is produced on complete combustion of $16.8 \, L$ gaseous mixture of ethene $(C_2H_4)$ and methane $(CH_4)$ at $25^{\circ}C$ and $1 \, atm$. Heat evolved during the combustion process is $......... \, kJ$.
Given :
$\Delta H_C(CH_4) = -900 \, kJ \, mol^{-1}$
$\Delta H_C(C_2H_4) = -1400 \, kJ \, mol^{-1}$

Heat of combustion of $CH_4, C_2H_4$ and $C_2H_6$ are $-890, -1411$ and $-1560 \ kJ/mol$ respectively. Which has the lowest calorific value?

An organic compound $C_xH_yO_z$ on complete combustion provides equivolume of products $CO_{2(g)}$ and $H_2O_{(g)}$,which is individually double the volume of the organic compound taken. In the process,the volume of oxygen consumed is the same as the volume of $CO_2$ produced,and the liberated heat during combustion is $500 \ kcal/mol$ at constant pressure and $500 \ K$. The formula of the organic compound and $\Delta U$ for the reaction will be:

$A$ $10 \ g$ piece of iron $(C = 0.45 \ J/g \ ^oC)$ at $100 \ ^oC$ is dropped into $25 \ g$ of water $(C = 4.2 \ J/g \ ^oC)$ at $27 \ ^oC$. Find the temperature of the iron and water system at thermal equilibrium in $^oC$.

$A$ gas (Molar mass $= 280 \ g \ mol^{-1}$) was burnt in excess $O_2$ in a constant volume calorimeter and during combustion the temperature of calorimeter increased from $298.0 \ K$ to $298.45 \ K$. If the heat capacity of calorimeter is $2.5 \ kJ \ K^{-1}$ and enthalpy of combustion of gas is $9 \ kJ \ mol^{-1}$,then the amount of gas burnt is $...... \ g$. (Nearest Integer)

The enthalpies of combustion of carbon and carbon monoxide are $-393.5 \, kJ \, mol^{-1}$ and $-283 \, kJ \, mol^{-1}$ respectively. The enthalpy of formation of carbon monoxide per mole is $....... \, kJ \, mol^{-1}$. (in $.5$)