If $30 \ mL$ of $H_2$ and $20 \ mL$ of $O_2$ react to form water,what is left at the end of the reaction?

In Ostwald's process for the manufacture of nitric acid,the first step involves the oxidation of ammonia gas by oxygen gas to give nitric oxide gas and steam. What is the maximum weight of nitric oxide that can be obtained starting only with $10.00 \ g$ of ammonia and $20.00 \ g$ of oxygen?

The amount of $BaSO_4$ formed upon mixing $100 \ mL$ of $20.8 \%$ $BaCl_2$ solution with $50 \ mL$ of $9.8 \%$ $H_2SO_4$ solution will be ............. $g$
( $Ba = 137, Cl = 35.5, S = 32, H = 1$ and $O = 16$ )

For the reaction $2Al + 3MnO \xrightarrow{\Delta} Al_2O_3 + 3Mn$; If $108 \ g$ of $Al$ and $213 \ g$ of $MnO$ are heated,then which of the following is incorrect?

Production of iron in a blast furnace follows the following equation:
$Fe_{3}O_{4(s)} + 4CO_{(g)} \rightarrow 3Fe_{(s)} + 4CO_{2(g)}$
When $4.640 \ kg$ of $Fe_{3}O_{4}$ and $2.520 \ kg$ of $CO$ are allowed to react,the amount of iron (in $g$) produced is $....$
[Given: Molar Atomic mass $(g \ mol^{-1}): Fe = 56, O = 16, C = 12$]

In the reaction: $4A + 2B + 3C \to A_4B_2C_3,$ what will be the number of moles of product formed,starting from $1 \, mole$ of $A, 0.6 \, mole$ of $B$ and $0.72 \, mole$ of $C$?