The mass of one mole of a substance in grams is called ....... .

$1 \, g$ of hydrogen combines with $80 \, g$ of bromine,and $1 \, g$ of calcium combines with $4 \, g$ of bromine. What is the equivalent weight of calcium?

Many elements have non-integral atomic masses because:

$A$ metal $M$ (specific heat $0.16 \ J \ g^{-1} \ K^{-1}$) forms a metal chloride with $65\%$ chlorine present in it. The formula of the metal chloride will be:

The average molecular weight of the air which has $21 \%$ of $O_2$ and $79 \%$ of $N_2$,is

Suppose two elements $X$ and $Y$ combine to form two compounds $XY_{2}$ and $X_{2}Y_{3}$. If $0.05 \ mol$ of $XY_{2}$ weighs $5 \ g$ while $3.011 \times 10^{23}$ molecules of $X_{2}Y_{3}$ weighs $85 \ g$,then atomic masses of $X$ and $Y$ are respectively :