How many $g$ of bromine will react with $21\, g$ of $C_3H_6$?

Concentrated sulfuric acid is $95\%$ by weight and its density is $1.8 \ g \ cm^{-3}$. What volume of concentrated acid in $cm^3$ is required to prepare $4 \ L$ of $0.4 \ M \ H_2SO_4$ solution (in $.7$)?

Equal masses of methane $(CH_4)$ and oxygen $(O_2)$ are mixed in an empty container at $25\,^oC$. The fraction of the total pressure exerted by oxygen is:

$19 \ g$ of a mixture containing $NaHCO_3$ and $Na_2CO_3$ on complete heating liberated $1.12 \ L$ of $CO_2$ at $STP$. The weight of the remaining solid was $15.9 \ g$. What is the weight (in $g$) of $Na_2CO_3$ in the mixture before heating?

The molar solution of sulphuric acid is equal to:

If a mixture of $340 \ g$ of $N_2$ and $H_2$ in the stoichiometric ratio yields $20\%$ $NH_3$ by mass,what is the mass of $NH_3$ produced in $g$?