If the molecular mass and atomic mass of sulphur are $256$ and $32$ respectively,its atomicity is:

An alloy of metals $X$ and $Y$ weighs $12 \ g$ and contains atoms $X$ and $Y$ in the ratio of $2:5$. The percentage of metal $X$ in the alloy is $20$ by mass. If the atomic mass of $X$ is $40$,what is the atomic mass of metal $Y$ (in $amu$)?

The equivalent weight of $H_3PO_4$ in the reaction is $Ca(OH)_2 + H_3PO_4 \to CaHPO_4 + 2H_2O$
$(Ca = 40, P = 31, O = 16)$

The amount of $K_2Cr_2O_7$ (equivalent weight $49.04$) required to prepare $100 \ mL$ of its $0.05 \ N$ solution is ........ $g$.

What do you mean by molar weight?

Which one of the following properties of an element is not variable?