What quantity of carbon dioxide is produced when $2 \,mol$ of carbon is burnt in $16 \,g$ of dioxygen (in $\,g$)?

According to the reaction $2A + B \to C$,$8 \ mol$ of $A$ and $5 \ mol$ of $B$ will produce how many moles of $C$?

If $5$ moles of $BaCl_2$ is mixed with $2$ moles of $Na_3PO_4$,the maximum number of moles of $Ba_3(PO_4)_2$ formed is $..........$ (Nearest integer)

$CaCO_3 + 2HCl \to CaCl_2 + CO_2 + H_2O$. In this chemical reaction,what will be the amount of $CaCl_2$ produced when $10 \ g$ of calcium carbonate and $200 \ mL$ of $0.75 \ M$ $HCl$ are used? $.............. \ g$

How much amount of $Al_2O_3$ will be formed when $5.4 \ g$ of $Al$ reacts with $10 \ g$ of $O_2$? .......... $g$

$250 \ mL$ of $0.5 \ M \ NaOH$ was added to $500 \ mL$ of $1 \ M \ HCl$. The number of unreacted $HCl$ molecules in the solution after complete reaction is $...... \times 10^{21}$. (Nearest integer) $(N_{A} = 6.022 \times 10^{23})$