Consider the reaction shown below where $6.1 \,g$ of benzoic acid is used to obtain $7.8 \,g$ of $m$-bromobenzoic acid. The percentage yield of the product is ....... .
(Round off to the Nearest integer) [Given : Atomic masses : $C = 12.0 \,u, H = 1.0 \,u, O = 16.0 \,u, Br = 80.0 \,u$]

$x \ mg$ of pure $HCl$ was used to make an aqueous solution. $25.0 \ mL$ of $0.1 \ M$ $Ba(OH)_2$ solution is used when the $HCl$ solution was titrated against it. The numerical value of $x$ is . . . . . . $\times 10^{-1}$. (Nearest integer)
Given: Molar mass of $HCl$ and $Ba(OH)_2$ are $36.5$ and $171.0 \ g \ mol^{-1}$ respectively.

$A$ sample of $CaCO_3$ and $MgCO_3$ weighing $2.21 \ g$ is ignited to a constant weight of $1.152 \ g$. The composition of the mixture is:
(Given molar mass in $g \ mol^{-1}: CaCO_3 = 100, MgCO_3 = 84$)

$2 \ g$ of aluminium is treated separately with excess of dilute $H_{2}SO_{4}$ and excess of $NaOH$. The ratio of the volumes of hydrogen evolved is

$0.53 \ g$ of $Na_2CO_3$ has been dissolved in $100 \ mL$ of a sodium carbonate solution. The normality of the solution will be

$6.023 \times 10^{22}$ molecules are present in $10 \ g$ of a substance $'x'.$ The molarity of a solution containing $5 \ g$ of substance $'x'$ in $2 \ L$ solution is.......... $\times 10^{-3}$