Question

Which one of the following pairs of reactants does not produce oxygen when they react with each other?

• A. $F_2,NaOH$ solution (hot, conc.)
• B. $F_2,H_{2}O$
• C. ${Cl}_2,NaOH$ solution (cold, dilute)
• D. $CaOC{l}_2,H_{2}S{O}_4$ (dilute, small amount)

Answer 1

The correct option is C ${Cl}_2,NaOH$ solution (cold, dilute)

1. Fluorine reacts with hot concentrated $NaOH$ solution to form oxygen.

The reaction is as follows:

$10F_2+20NaOH\to 20NaF+10O_2+H_{2}O$

2. Fluorine reacts with water to form oxygen.

$2F_2+2H_{2}O\to O_2+4F^{-}+4H^{+}$.

3. Chlorine reacts with cold dilute $NaOH$ solution to form sodium chloride, sodium hypochloride and water. Oxygen is not formed in the reaction.

$C{l}_2+NaOH\to NaCl+NaOCl+H_{2}O$

4. $CaOC{l}_2$ reacts with small amount of dilute $H_{2}S{O}_4$ to produce oxygen.

$2CaOC{l}_2+H_{2}S{O}_4\to CaC{l}_2+CaS{O}_4+2HClO$
$HClO\to HCl+O$

Hence, the only reaction among the four which produce no oxygen is between $C{l}_2$ and $NaOH$ (cold, dilute).

Hence, the correct option is C.