If the mass table of atomic weights were established with oxygen atom assigned a value of $100,$ the atomic weight of carbon would be

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 $.5$)?

The equivalent weights of $H_3PO_4$ in the following reactions are respectively:
$H_3PO_4 + OH^{-} \rightarrow H_2PO_4^- + H_2O$
$H_3PO_4 + 2OH^{-} \rightarrow HPO_4^{2-} + 2H_2O$
$H_3PO_4 + 3OH^{-} \rightarrow PO_4^{3-} + 3H_2O$

The equivalent weight of $H_3PO_4$ in the reaction is $Ca(OH)_2 + H_3PO_4 \to CaHPO_4 + 2H_2O$
$(Ca = 40, P = 31, O = 16)$

$16.25 \ g$ of metal chloride is obtained on complete conversion of $8 \ g$ of metal oxide into metal chloride. What will be the equivalent weight of the metal?

$12 \ g$ of an element reacts with $32 \ g$ of oxygen. What is the equivalent weight of the element?