$A$ $100 \ mL$ solution was made by adding $1.43 \ g$ of $Na_2CO_3 \cdot xH_2O$. The normality of the solution is $0.1 \ N$. The value of $x$ is .......... (The atomic mass of $Na$ is $23 \ g/mol$):

To a $25 \, mL$ of $H_2O_2$ solution,an excess of acidified solution of $KI$ was mixed. The liberated $I_2$ required $20 \, mL$ of $0.3 \, M$ hypo $(Na_2S_2O_3)$ solution for neutralization. The volume strength of $H_2O_2$ is......$mL$.

Find the weight in grams of carbon monoxide $(CO)$ that contains the same number of oxygen atoms as are present in $22 \ g$ of carbon dioxide $(CO_2)$.

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 ....... $kg$.

If $25 \ mL$ of a $H_2SO_4$ solution is neutralized by $32.63 \ mL$ of $0.164 \ M \ NaOH$ solution,what is the molarity of the $H_2SO_4$ solution (in $M$)?

What is produced when $1 \ mol$ of calcium phosphide reacts with excess water?
$(Hint: Ca_3P_2 + H_2O (excess) \rightarrow Ca(OH)_2 + 2PH_3)$