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

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 $......... \, litres.$

In which of the following reactions is no gas evolved on the product side? (Temperature is maintained below the boiling point of liquids formed)

Iron sulphide is heated in air to form $A$,an oxide of sulphur. $A$ is dissolved in water to give an acid. The basicity of this acid is

Which one of the following is the lightest?

An aqueous solution of $6.3 \ g$ oxalic acid dihydrate is made up to $250 \ mL$. The volume of $0.1 \ N \ NaOH$ required to completely neutralize $10 \ mL$ of this solution is $...... \ mL$.