Correct Answer - Option 2 : 25 ml

__Concept__:

The reaction of HCl with Na_{2}CO_{3} is as follows:

2HCl + Na_{2}CO_{3 }→ 2NaCl + H_{2}O + CO_{2}

We know that, M_{eq} of HCl = M_{eq} of Na_{2}CO_{3}

\(\frac{{25}}{{1000}} \times 1 \times {M_{{\rm{HCl}}}} = \frac{{30}}{{1000}} \times 0.1 \times 2\)

\({M_{{\rm{HCl}}}} = \frac{{30 \times 0.2}}{{25}} = \frac{6}{{25}}{\rm{M}}\)

The reaction of HC with NaOH is as follows:

NaOH + HC → NaC + H_{2}O

Also, M_{eq} of HCl = M_{eq} of NaOH

\(\frac{6}{{25}} \times 1 \times \frac{V}{{1000}} = \frac{{30}}{{1000}} \times 0.2 \times 1\)

**V = 25 ml.**