Vapour density of a metal chloride is $66$. Its oxide contains $53\%$ metal. The atomic weight of the metal is

The equivalent mass of a metal is $29.73$ and the vapour density of its chloride is $130.4$. Find out the atomic mass of the metal.

Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes:

Isotope	Isotopic molar mass $(g \, mol^{-1})$	Abundance (%)
$^{36}Ar$	$35.96755$	$0.337$
$^{38}Ar$	$37.96272$	$0.063$
$^{40}Ar$	$39.9624$	$99.600$

$A$ metal oxide is reduced by heating it in a stream of hydrogen. It is found that after complete reduction,$3.15 \, g$ of the oxide yielded $1.05 \, g$ of the metal. We may deduce that:

When the weights of two elements combine with each other,their ratio is the ratio of their ......

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