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

In the reaction $SO_2 + 2H_2S \rightarrow 3S + 2H_2O$,the equivalent mass of the oxidizing agent is .....

The atomic mass of noble gases is determined by which of the following relationships?

Complete reaction of $2.0 \, g$ of calcium (at. wt. $= 40$) with excess $HCl$ produces $1.125 \, L$ of $H_2$ gas. Complete reaction of the same quantity of another metal $M$ with excess $HCl$ produces $1.85 \, L$ of $H_2$ gas under identical conditions. The equivalent weight of $M$ is closest to

The unit of atomic mass,$amu$ is replaced by $u$,here $u$ stands for

If we consider that $1/6$ of the mass of a carbon atom,in place of $1/12$,is taken to be the relative atomic mass unit,the mass of one mole of a substance will