What will be the equivalent weight of a metal if the vapour density of the chloride salt of a trivalent metal is $81.25$?

If $V \ mL$ of the vapours of a substance at $NTP$ weigh $W \ g$,find the molecular weight of the substance.

The equivalent weight of an acid:

In chlorine,the isotopes $^{35}Cl$ and $^{37}Cl$ are present in the ratio $3:1$. Calculate the atomic mass of chlorine. (in $amu$)

$4 \ g$ 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

Write the formulae for the following compounds:
$(a)$ Mercury $(II)$ chloride
$(b)$ Nickel $(II)$ sulphate
$(c)$ Tin $(IV)$ oxide
$(d)$ Thallium $(I)$ sulphate
$(e)$ Iron $(III)$ sulphate
$(f)$ Chromium $(III)$ oxide