$20$ moles of $A$ and $14$ moles of $B$ are mixed and allowed to react according to the equation $A + 2B \rightarrow 3C$. What is the maximum number of moles of $C$ which could be prepared?

One mole of $Cl_{2(g)}$ was passed into $2 \text{ L}$ of cold $2 \text{ M}$ $KOH$ solution. After the reaction, the concentrations of $Cl^{-}$, $ClO^{-}$ and $OH^{-}$ are respectively (assume volume remains constant):

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

$250 \ mL$ 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) $(N_{A} = 6.022 \times 10^{23})$

The amount of heat evolved when $500 \text{ cm}^{3}$ of $0.1 \text{ M } HCl$ is mixed with $200 \text{ cm}^{3}$ of $0.2 \text{ M } NaOH$ is (in $\text{ kJ}$)

How many moles of $PbCl_2$ will be obtained from the reaction between $6.5 \ g$ of $PbO$ and $3.2 \ g$ of $HCl$?