If the percentage of $Se$ (atomic weight $78.4$) in a peroxidase anhydrous enzyme is $0.5\%$,what is the minimum molecular weight of the peroxidase anhydrous enzyme?

$4 \ g$ 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?

On reduction with hydrogen,$3.6 \ g$ of an oxide of metal $(M)$ left $3.2 \ g$ of the metal. If the atomic weight of the metal is $64$,the formula of the oxide is:

The empirical formula of a compound is $C_2H_5O$ and its molecular weight is $90$. The molecular formula of the compound is:

What is the percentage of nitrogen in urea (in $\%$)?

On analysis,a certain compound was found to contain iodine and oxygen in the ratio of $254 \ g$ of iodine and $80 \ g$ of oxygen. The atomic mass of iodine is $127$ and that of oxygen is $16$. Which of the following is the formula of the compound?