Substance $A_2B_{(g)}$ can undergo decomposition to form two sets of products. If the molar ratio of $A_{2(g)}$ to $A_{(g)}$ is $5 : 3$ in a set of product gases,then the energy involved in the decomposition of $1 \, \text{mole}$ of $A_2B_{(g)}$ is:
$A_2B_{(g)} \to A_{2(g)} + B_{(g)}; \Delta H^o = 40 \, \text{kJ/mol}$
$A_2B_{(g)} \to A_{(g)} + AB_{(g)}; \Delta H^o = 50 \, \text{kJ/mol}$

$10 \ mL$ of $2 \ M$ $NaOH$ solution is added to $20 \ mL$ of $1 \ M$ $HCl$ solution kept in a beaker. Now,$10 \ mL$ of this mixture is poured into a volumetric flask of $100 \ mL$ containing $2 \ moles$ of $HCl$ and made the volume up to the mark with distilled water. The solution in this flask is $:$

Mole fraction of $O_2$ in $O_2$ and $O_3$ mixture is $0.25$. Hence percentage concentration $\left( \frac{w}{W} \% \right)$ of $O_2$ in the mixture is:

Assume that a human body requires $2500 \, kcal$ of energy each day for metabolic activity and sucrose is the only source of energy,as per the equation $C_{12}H_{22}O_{11(s)} + 12 \, O_{2(g)} \longrightarrow 12 \, CO_{2(g)} + 11 \, H_2O_{(l)};$ $\Delta H = -5.6 \times 10^6 \, J$. (Fill in the blanks) $(a)$ The energy requirement of the human body per day is $.... \, kJ$. $(b)$ The mass of sucrose required to provide this energy is $........ \, g$ and the volume of $CO_2$ (at $STP$) produced is $......... \, litres.$

$A$ mixture of hydrogen and oxygen contains $20\%$ by weight of hydrogen. Find the total number of molecules per gram of the mixture.

$H_2O_2$ solution used for hair bleaching is sold as a solution of approximately $5.0 \, g$ $H_2O_2$ per $100 \, mL$ of the solution. The molecular mass of $H_2O_2$ is $34$. The molarity of this solution is approximately $........$ $M$.