The density of $SO_2$ at $STP$ is ......... $g/L$.

$24 \ g$ of $Mg$ metal reacts with water. How many moles of $H_2$ will be liberated? ............. $mol$

$1.86 \ g$ of aniline completely reacts to form acetanilide. $10 \ \%$ of the product is lost during purification. Amount of acetanilide obtained after purification (in $g$) is ...... $\times 10^{-2}$.

The chloride of a metal is $MCl_2$. The formula of its phosphate will be:

Sodium oxide reacts with water to produce sodium hydroxide. $20.0 \ g$ of sodium oxide is dissolved in $500 \ mL$ of water. Neglecting the change in volume,the concentration of the resulting $NaOH$ solution is $........ \times 10^{-1} \ M.$ (Nearest integer)
[Atomic mass $: Na=23.0, O=16.0, H=1.0]$

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 ....... $kg$.