The volume of hydrogen liberated at $STP$ by treating $2.4 \ g$ of magnesium with excess of hydrochloric acid is $x \times 10^{-2} \ L$. Find the value of $x$. Given: Molar volume of gas is $22.4 \ L$ at $STP$. Molar mass of magnesium is $24 \ g \ mol^{-1}$.

What is the weight of $H_2SO_4$ (in $g$) required to completely dissolve $3 \ g$ of magnesium carbonate?

$50 \ mL$ of $0.5 \ M$ oxalic acid is needed to neutralize $25 \ mL$ of sodium hydroxide solution. The amount in grams of $NaOH$ in $50 \ mL$ of the given sodium hydroxide solution is:

$NaClO_{3}$ is used,even in spacecrafts,to produce $O_{2}.$ The daily consumption of pure $O_{2}$ by a person is $492 \ L$ at $1 \ atm, 300 \ K.$ How much amount of $NaClO_{3},$ in grams,is required to produce $O_{2}$ for the daily consumption of a person at $1 \ atm, 300 \ K?$
$2NaClO_{3(s)} + Fe_{(s)} \rightarrow 3O_{2(g)} + 2NaCl_{(s)} + FeO_{(s)}$
$R = 0.082 \ L \ atm \ mol^{-1} K^{-1}$

Haemoglobin contains $0.33\%$ of iron by weight. The molecular weight of haemoglobin is approximately $67200$. The number of iron atoms (At. wt. of $Fe = 56$) present in one molecule of haemoglobin is

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 ....... $kg$.