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

The equivalent weight of an element is $4$. Its chloride has a $V.D$ of $59.25$. Then the valency of the element is:

The equivalent weight of $K_2Cr_2O_7$ in acidic medium is:

If $A_1 \ g$ of an element gives $A_2 \ g$ of its oxide,then the equivalent mass of the element is .....

The atomic mass of an element is $27$. If its valency is $3$,what is the vapor density of its volatile chloride?

$0.1914 \ g$ of an organic acid is dissolved in approx. $20 \ mL$ of water. $25 \ mL$ of $0.12 \ N$ $NaOH$ is required for the complete neutralization of the acid solution. The equivalent weight of the acid is