How many moles of $P_4$ can be produced by reaction of $0.10 \ mol$ $Ca_5(PO_4)_3F$,$0.36 \ mol$ $SiO_2$,and $0.90 \ mol$ $C$ according to the following reaction?
$4Ca_5(PO_4)_3F + 18SiO_2 + 30C \to 3P_4 + 2CaF_2 + 18CaSiO_3 + 30CO$

Which of the following is formed when calcium combines with oxygen?

In a closed vessel at $STP$,$50 \, L$ of $CH_4$ is ignited with $750 \, L$ of air (containing $20 \% \ O_2$). The number of moles of $O_2$ remaining in the vessel on cooling to room temperature is closest to

$56 \ g$ of $CaO$ has been mixed with $63 \ g$ of $HNO_3$. The amount of $Ca(NO_3)_2$ formed is: (in $g$)

$1.0 \ g$ of magnesium is burnt with $0.56 \ g \ O_2$ in a closed vessel. Which reactant is left in excess and how much? (At. $wt. \ Mg = 24, O = 16$)

Aluminium reacts with sulfuric acid to form aluminium sulfate and hydrogen. What is the volume of hydrogen gas in liters $(L)$ produced at $300 \ K$ and $1.0 \ atm$ pressure,when $5.4 \ g$ of aluminium and $50.0 \ mL$ of $5.0 \ M$ sulfuric acid are combined for the reaction?
(Use molar mass of aluminium as $27.0 \ g \ mol^{-1}, R = 0.082 \ atm \ L \ mol^{-1} \ K^{-1}$)