The most abundant elements by mass in the body of a healthy human adult are: Oxygen $(61.4\%);$ Carbon $(22.9\%),$ Hydrogen $(10.0\%);$ and Nitrogen $(2.6\%).$ The weight which a $75 \ kg$ person would gain if all $^1H$ atoms are replaced by $^2H$ atoms is ....... $kg$.

The normality of $1 \ M$ solution of $H_3PO_4$ will be.....$N$

$A$ mixture of $NO_2$ and $N_2O_4$ has a vapour density of $38.3$ at $270,^oC$. Calculate the number of moles of $NO_2$ in $100$ moles of the mixture.

Excess of $NaOH\, (aq)$ was added to $100\, mL$ of $FeCl_3\, (aq)$ resulting in $2.14\, g$ of $Fe(OH)_3$. The molarity of $FeCl_3\, (aq)$ is (Given molar mass of $Fe=56\, g\, mol^{-1}$ and molar mass of $Cl=35.5\, g\, mol^{-1}$) (in $, M$)

Suppose a cooking gas cylinder contains $11.2 \, kg$ of isobutane. The thermochemical equation for the combustion of butane is given below:
$C_4H_{10}(g) + \frac{13}{2} O_2(g) \to 4CO_2(g) + 5H_2O(\ell); \Delta H = -2658 \, kJ$
If a family requires $15000 \, kJ$ of energy per day for cooking,how many days will the cylinder last?

How much water is needed to dilute $10 \, mL$ of $10 \, N$ hydrochloric acid to make it exactly decinormal $(0.1 \, N)$? .......... $mL$