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

$3.011 \times 10^{22}$ atoms of an element weigh $1.15 \ g$. The atomic mass of the element is: (in $amu$)

In Victor Mayer’s method,$0.2 \ g$ of an organic substance displaced $56 \ mL$ of air at $STP$. The molecular weight of the compound is:

Assertion : Equivalent weight of a base $= \frac{\text{Molecular weight}}{\text{Acidity}}$
Reason : Acidity is the number of replaceable hydrogen atoms in one molecule of the base.

The equivalent weight of an acid:

$1.520 \ g$ of the hydroxide of a metal on ignition gave $0.995 \ g$ of oxide. The equivalent weight of the metal is: