When $20 \ g$ of $CaCO_3$ is treated with $20 \ g$ of $HCl$,the mass of $CO_2$ formed would be: (in $g$)

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

$5 \ mL$ of $0.1 \ M \ Pb(NO_{3})_{2}$ is mixed with $10 \ mL$ of $0.02 \ M \ KI$. The amount of $PbI_{2}$ precipitated will be about

$0.5 \ mol$ of $H_2SO_4$ is mixed with $0.2 \ mol$ of $Ca(OH)_2$. What is the maximum number of moles of $CaSO_4$ formed?

$A + 2B + 3C \rightleftharpoons AB_2C_3$. Reaction of $6.0 \ g$ of $A$,$6.0 \times 10^{23}$ atoms of $B$,and $0.036 \ mol$ of $C$ yields $4.8 \ g$ of compound $AB_2C_3$. If the atomic mass of $A$ and $C$ are $60$ and $80 \ amu$,respectively,the atomic mass of $B$ is .............. $amu$ (Avogadro no. $= 6 \times 10^{23}$)

Calculate the amount of carbon dioxide that could be produced when
$(i)$ $1$ mole of carbon is burnt in air.
$(ii)$ $1$ mole of carbon is burnt in $16 \ g$ of dioxygen.
$(iii)$ $2$ moles of carbon are burnt in $16 \ g$ of dioxygen.