What is the ratio of the active masses of $22 \ g$ $CO_2$,$3 \ g$ $H_2$,and $7 \ g$ $N_2$ in a gaseous mixture?

How much oxygen is required for complete combustion of $560 \ g$ of ethene? ................. $kg$

$24 \ g$ of $Mg$ metal reacts with water. How many moles of $H_2$ will be liberated? ............. $mol$

$A$ $40 \%$ $HCl$ solution has density $1.2 \ g \ mL^{-1}$. The molarity of the solution is nearly . . . . . . (in $M$)

What volume of ammonia is formed when $10 \ dm^3$ dinitrogen reacts with $30 \ dm^3$ dihydrogen at same temperature and pressure (in $dm^3$)?

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time,the passage of air is stopped,but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$) of $Pb$ produced per $kg$ of $O_2$ consumed is $. . . . .$ (Atomic weights in $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)