The equivalent weight of a certain trivalent element is $20$. The molecular weight of its oxide is:

In a copper sulfate solution,$3.2 \ g$ of copper is displaced by $2.8 \ g$ of iron. If the equivalent mass of iron is $28$,what is the equivalent mass of copper?

An oxide of an element contains $20 \%$ oxygen by weight. Calculate the equivalent weight of the element.

$A$ gas has the formula $(CO)_x$. Its vapour density is $70$. What is the value of $x$?

$A$ mixture of $1.65 \times 10^{21}$ molecules of $X$ and $1.85 \times 10^{21}$ molecules of $Y$ weighs $0.688 \ g$. If the molecular mass of $Y$ is $187 \ g/mol$,what is the molecular mass of $X$?

If the weight of $1 \ L$ of a gas is $2 \ g$,then its vapor density and molecular weight are respectively .....