Question

A dilute solution of sodium carbonate was added to two test tubes - one containing dilute $HCl$ (A) and the other containing dilute $NaOH$ (B). The correct observation was

• A. A brown coloured gas liberated in test tube A.
• B. A brown coloured gas liberated in test tube B.
• C. A colourless gas liberated in test tube A.
• D. A colourless gas liberated in test tube B.

Answer 1

The correct option is C

A colourless gas liberated in test tube A.

$N{a}_{2}C{O}_3\left(aq\right)+2HCl\left(aq\right)\to 2NaCl\left(aq\right)+C{O}_2\uparrow +H_{2}O\left(l\right)$
$C{O}_2$ is a colourless and odourless gas.
$N{a}_{2}C{O}_3+NaOH\to Noreaction$
$N{a}_{2}C{O}_3$ is a basic salt and hence it reacts with $HCl$ (strong acid) to form $NaCl$, whereas it undergoes no reaction when it reacts with a strong base like $NaOH$.