Atomic weight of $Ne$ is $20.2$. If $Ne$ is a mixture of $Ne^{20}$ and $Ne^{22}$,what is the percentage abundance of the lighter isotope?

The mass of $500 \, cm^3$ of a gas at $STP$ is $0.581 \, g$. If the gas is a hydrocarbon,what is the gas?

The relative abundances of two isotopes of rubidium with atomic masses $85$ and $87$ are $75\%$ and $25\%$ respectively. What is the average atomic mass of rubidium (in $.5$)?

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

What will be the mass of one atom of $^{12}C$ in grams?

$4 \ g$ 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