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

Which of the following pairs of species has the same percentage of carbon?

The empirical formula of a compound is $C_2H_5O$ and its vapour density is $45$. What is the molecular formula of the compound?

On complete combustion,$1.0 \ g$ of an organic compound $(X)$ gave $1.46 \ g$ of $CO_2$ and $0.567 \ g$ of $H_2O$. The empirical formula mass of compound $(X)$ is $.......... \ g \ mol^{-1}$. (Given molar mass in $g \ mol^{-1}: C: 12, H: 1, O: 16$)

$4 \ g$ of a hydrocarbon on complete combustion gave $12.571 \ g$ of $CO_2$ and $5.143 \ g$ of water. What is the empirical formula of the hydrocarbon?

$0.765 \ g$ of an acid gives $0.535 \ g$ of $CO_2$ and $0.13 \ g$ of $H_2O$. The ratio of the percentage of $C$ and $H$ is: