In $1 \ g$ of a metal oxide,the mass of metal precipitated is $0.68 \ g$. What is the equivalent weight of the metal?

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......$amu$.

The density of liquid ethanol is $0.929 \, g \, cm^{-3}$. What is the volume occupied by one mole of ethanol molecules?

If we consider that $1/6$ of the mass of a carbon atom,in place of $1/12$,is taken to be the relative atomic mass unit,the mass of one mole of a substance will

$A$ mixture of $1.65 \times 10^{21}$ molecules of $X$ and $1.85 \times 10^{21}$ molecules of $Y$ weighs $0.688 \ g$. If the molecular mass of $Y$ is $187 \ g/mol$,what is the molecular mass of $X$?

When an element forms its oxide,oxygen constitutes $20\%$ of its weight in the oxide. What is the equivalent weight of the element?