The normality of orthophosphoric acid having purity of $70\%$ by weight and specific gravity $1.54$ would be ............. $N$.

How many grams of ethanol are required to obtain $280 \ mL$ of dihydrogen gas at $S.T.P.$ by the reaction of $C_2H_5OH$ with $Na$ metal? (Molar mass of ethanol = $46 \ g/mol$)

How much of $NaOH$ (in $g$) is required to neutralize $1500 \ cm^3$ of $0.1 \ N \ HCl$? (Given: $Na = 23, O = 16, H = 1$)

The density of a gas at $STP$ is $2.86 \, g \, L^{-1}$. Which of the following is the gas?

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in $grams$) of the salt required to achieve $10 \; ppm$ of iron in $100 \; kg$ of wheat is
Atomic weight : $Fe = 55.85$,$S = 32.0$,$O = 16.00$

$2.5 \ cm^{3}$ of $0.2 \ M \ H_{2}SO_{4}$ solution is diluted to $0.5 \ dm^{3}$. Find the normality of the diluted solution. (in $N$)