Naturally occurring boron has $20\%\, _5B^{10}$ and $80\%\, _5B^{11}$. The atomic weight of boron is :-

$A$ metal oxide has $40\%$ oxygen by mass. The equivalent weight of the metal is:

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

If a metal oxide contains $32\%$ oxygen,what is the equivalent mass of the metal?

$71 \ g$ of chlorine combines with a metal to form $111 \ g$ of its chloride. The chloride is isomorphous with $MgCl_2 \cdot 6H_2O$. The atomic weight of the metal is:

$0.45 \ g$ of an acid (mol wt. $= 90$) required $20 \ mL$ of $0.5 \ N$ $KOH$ for complete neutralization. The basicity of the acid is: