When the weights of two elements combine with each other,their ratio is the ratio of their ......

The equivalent mass of an element is $4$ and the vapor density of its chloride is $59.25$. Find the valency of the element.

Among $10^{-9} \ g$ (each) of the following elements,which one will have the highest number of atoms?
Element: $Pb, Po, Pr$ and $Pt$

$10 \text{ g}$ of a metal $(M)$ reacts with oxygen to form $11.6 \text{ g}$ of oxide. What is the equivalent weight of $M$?

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

$4 \ g$ of copper was dissolved in concentrated nitric acid. The copper nitrate solution on strong heating gave $5 \ g$ of its oxide. The equivalent weight of copper is