The unit of atomic weight is

Naturally occurring boron consists of two isotopes with atomic masses $10.01 \ (I)$ and $11.01 \ (II)$. The average atomic mass of natural boron is $10.81$. Find the percentage abundance of isotopes $(I)$ and $(II)$ respectively.

An element,$X$ has the following isotopic composition:
$^{200}X: 90\%$,$^{199}X: 8.0\%$,$^{202}X: 2.0\%$
The weighted average atomic mass of the naturally occurring element $X$ is closest to......$amu$.

$71 \ g$ 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:

The average molar mass of chlorine is $35.5 \ g \ mol^{-1}$. The ratio of $^{35}Cl$ to $^{37}Cl$ in naturally occurring chlorine is close to : (in $:1$)

In order to prepare one litre of a $1 \ N$ (normal) solution of $KMnO_4$,how many grams of $KMnO_4$ are required if the solution is to be used in an acidic medium for oxidation?