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:

Empirical formula of a compound is $CH_2O$ and its vapour density is $30$. The molecular formula of the compound is:

One compound contains $4.07\%$ Hydrogen,$24.47\%$ Carbon and $71.65\%$ Chlorine. Its molar mass is $98.96\ g/mol$. Find the empirical formula and molecular formula.

Insulin contains $3.4\%$ sulphur. The minimum molecular weight of insulin is

$A$ compound contains $2.2 \ g$ of phosphorus and $1.24 \ g$ of sulfur. What is its empirical formula?

Arrange the following compounds in the increasing order of percentage of chlorine by weight:
$I.$ $DDT$ $(C_{14}H_9Cl_5)$
$II.$ Gammaxene $(C_6H_6Cl_6)$
$III.$ Carbon tetrachloride $(CCl_4)$
$IV.$ Chlorobenzene $(C_6H_5Cl)$