The amount of heat evolved when $500 \text{ cm}^{3}$ of $0.1 \text{ M } HCl$ is mixed with $200 \text{ cm}^{3}$ of $0.2 \text{ M } NaOH$ is (in $\text{ kJ}$)

$100 \ g$ of propane is completely reacted with $1000 \ g$ of oxygen. The mole fraction of carbon dioxide in the resulting mixture is $x \times 10^{-2}$. The value of $x$ is ..... .
(Nearest integer)
[Atomic weight : $H=1.008$ ; $C=12.00$ ; $O=16.00$ ]

$1.0 \ g$ of $Mg$ is burnt with $0.28 \ g$ of $O_2$ in a closed vessel. Which reactant is left in excess and how much?

The set of numerical coefficients that balances the equation $K_2CrO_4 + HCl \to K_2Cr_2O_7 + KCl + H_2O$ is

$92 \ g$ of $NO_{2(g)}$ and $32 \ g$ of $O_{2(g)}$ are taken in a rigid container. At a constant temperature,they react to produce $N_2O_{5(g)}$. The pressure in the container after the reaction is observed to be $\frac{7}{8} P$,where $P$ is the initial pressure of the gaseous mixture. The percentage yield of the reaction is ....$\%$

The mass of water produced when $4 \ g$ of hydrogen reacts with $4 \ g$ of oxygen is .......... $g$.