$20 \ mL$ of $0.1 \ M$ $HCl$ is added to $30 \ mL$ of $0.1 \ M$ $NaOH$. To this solution,an extra $50 \ mL$ of water was added. What is the molarity of the final solution formed (in $M$)?

In the following reactions,identify $P, Q$ and $R$,respectively:
$I. 3Fe_2O_3 + CO \longrightarrow 2P + CO_2 \uparrow$
$II. Fe_3O_4 + 4CO \longrightarrow 3Q + 4CO_2 \uparrow$
$III. Fe_2O_3 + CO \longrightarrow 2R + CO_2 \uparrow$

What volume of hydrogen gas at $STP$ would be liberated by the action of $50 \text{ mL}$ of $H_2SO_4$ of $50\%$ purity (density = $1.3 \text{ g mL}^{-1}$) on $20 \text{ g}$ of zinc (in $L$)? Given: Molar mass of $H, O, S, Zn$ are $1, 16, 32, 65 \text{ g mol}^{-1}$ respectively.

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):

When burning magnesium ribbon is introduced into a jar of oxygen,it produces

Butane reacts with oxygen to produce carbon dioxide and water following the equation given below: $C_4H_{10(g)} + \frac{13}{2} O_{2(g)} \rightarrow 4 CO_{2(g)} + 5 H_2O_{(l)}$. If $174.0 \ kg$ of butane is mixed with $320.0 \ kg$ of $O_2$,the volume of water formed in litres is $...........$ (Nearest integer). [$Given$: $(a)$ Molar mass of $C, H, O$ are $12, 1, 16 \ g \ mol^{-1}$ respectively,$(b)$ Density of water $= 1 \ g \ mL^{-1}$]