If $6.022 \times 10^{20}$ atoms are present in $100 \ mL$ of urea solution,then find out the molarity of the urea solution. (in $M$)

$A$ mixture of gases contains $H_2$ and $O_2$ gases in the ratio of $1 : 4$ $(w/w)$. What is the molar ratio of the two gases in the mixture?

$X$ litres of carbon monoxide is present at $STP$. It is completely oxidized to $CO_2$. The volume of $CO_2$ formed is $11.207$ litres. What is the value of $X$ in litres?

$A$ metal chloride contains $55.0 \%$ of chlorine by weight. $100 \ mL$ of vapours of the metal chloride at $STP$ weigh $0.57 \ g$. The molecular formula of the metal chloride is $...$. (Given: Atomic mass of chlorine is $35.5 \ u$)

The density of a monobasic strong acid (Molar mass $24.2 \ g \ mol^{-1}$) is $1.21 \ kg \ L^{-1}$. The volume of its solution required for the complete neutralization of $25 \ mL$ of $0.24 \ M \ NaOH$ is $.............. \times 10^{-2} \ mL$ (Nearest integer).

$x \ g$ of methane was burnt completely in the presence of oxygen. The liberated gases were passed into a solution containing $370 \ g$ of $Ca(OH)_2$. The weight of white precipitate obtained was $500 \ g$. What is the value of $x$ (in $g$)? (Given: $C=12, H=1, Ca=40, O=16 \ u$)