Complete combustion of $3 \ g$ of ethane gives $x \times 10^{22}$ molecules of water. The value of $x$ is ......... (Round off to the Nearest Integer). [Use: $N_{A} = 6.023 \times 10^{23} ;$ Atomic masses in $u$ $C = 12.0, O = 16.0, H = 1.0$]

The volume of $2 \ N \ H_2SO_4$ solution is $0.1 \ dm^3$. The volume of its decinormal solution (in $dm^3$) will be

Excess of carbon dioxide is passed through $50 \ mL$ of $0.5 \ M$ calcium hydroxide solution. After the completion of the reaction,the solution was evaporated to dryness. The solid calcium carbonate was completely neutralized with $0.1 \ N$ hydrochloric acid. The volume of hydrochloric acid required is (Atomic mass of calcium $= 40$ ) (in $cm^{3}$)

The same mass of $CH_4$ and $H_2$ is taken in a container. The partial pressure caused by $H_2$ is:

An aqueous solution of $18 \ g$ oxalic acid $(H_2C_2O_4 \cdot 2H_2O)$ is made up to $400 \ mL$. Calculate the volume of $0.1 \ M \ NaOH$ required to completely neutralize $50 \ mL$ of the above solution in $mL$.

What is the percentage atom economy when the formula weight of the product obtained is $70 \ u$ and the sum of the formula weights of the reactants is $140 \ u$ (in $\%$)?