How much copper can be obtained from $100 \ g$ of copper sulfate $(CuSO_4)$ (in $g$)?

An oxide of iron contains $69.9\%$ iron. Its empirical formula is: (Given: Molar mass of $Fe$ and $O$ are $56$ and $16 \text{ g mol}^{-1}$ respectively.)

$A$ hydrocarbon contains $10.5 \, g$ of carbon and $1 \, g$ of hydrogen. If the volume of $2.4 \, g$ of this hydrocarbon is $1 \, L$ at $127 \, ^\circ C$ and $1 \, atm$ pressure,then the hydrocarbon is:

Complete combustion of $1.80 \, g$ of an oxygen-containing compound $(C_xH_yO_z)$ gave $2.64 \, g$ of $CO_2$ and $1.08 \, g$ of $H_2O$. The percentage of oxygen in the organic compound is

What is the molecular formula of the alkane,the $5.6 \, L$ of which weighs $11 \, g$ at $STP$?

The formula for calcium chlorite is