Question

A solution in test tube ‘A’ turns red litmus blue, involves hydrogen on reaction with zinc and does not react with sodium carbonate whereas the solution in test ‘B’ turns blue litmus red, liberated hydrogen on reaction with zinc and carbon dioxide with sodium carbonate, Solution took in A and B are:

• A. Acid in ‘A’, base in ‘B’
• B. Base in ‘A’, acid in ‘B’
• C. Base in both, ‘A’ and ‘B’
• D. Acid in both, ‘A’ and ‘B’

Answer 1

The correct option is B

Base in ‘A’, acid in ‘B’

The explanation for the correct option:

Option B is the correct option.

In test-tube A:

The solution present in test ‘A’ turns red litmus blue means it is a base.

And on reacting with zinc it releases hydrogen gas:

The following reaction is carried out:

$$\begin{gathered} \mathrm{X}+\underset{\left(\mathrm{Zinc}\right)}{\mathrm{Zn}\left(\mathrm{s}\right)}\to \mathrm{release}\mathrm{Hydrogen} \\ \mathrm{X}+\underset{(\mathrm{Sodium}\mathrm{carbonate})}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}\to \mathrm{does}\mathrm{not}\mathrm{react} \\ \mathrm{X}=\mathrm{NaOH} \\ \underset{\left(\mathrm{Sodium}\mathrm{hydroxide}\right)}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Zinc}\right)}{\mathrm{Zn}\left(\mathrm{s}\right)}\to \underset{\left(\mathrm{Sodium}\mathrm{zincate}\right)}{{\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Hydrogen}\mathrm{gas}\right)}{{\mathrm{H}}_2\left(\mathrm{g}\right)} \end{gathered}$$

In test-tube B:

The solution present in test tube ‘B’ turns blue litmus red means it is an acid.

And on reacting with sodium carbonate it liberates hydrogen.

$$\begin{gathered} \mathrm{Y}+\underset{(\mathrm{Sodium}\mathrm{carbonate})}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}\to \mathrm{it}\mathrm{liberates}{\mathrm{CO}}_2 \\ \mathrm{Y}\mathrm{is}\mathrm{HCl} \\ \underset{\left(\mathrm{Sodium}\mathrm{carbonate}\right)}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Hydrochloric}\mathrm{acid}\right)}{\mathrm{HCl}\left(\mathrm{l}\right)}\to \underset{\left(\mathrm{Sodium}\mathrm{chloride}\right)}{2\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Carbon}\mathrm{dioxide}\right)}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)} \\ \underset{\left(\mathrm{Sodium}\mathrm{chloride}\right)}{\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\left(\mathrm{Sodium}\mathrm{hydroxide}\right)}{\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Hydrochloric}\mathrm{acid}\right)}{\mathrm{HCl}\left(\mathrm{g}\right)} \\ \underset{\left(\mathrm{Sodium}\mathrm{hydroxide}\right)}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Zinc}\right)}{\mathrm{Zn}\left(\mathrm{s}\right)}\to \underset{\left(\mathrm{Sodium}\mathrm{zincate}\right)}{{\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Hydrogen}\mathrm{gas}\right)}{{\mathrm{H}}_2\left(\mathrm{g}\right)} \end{gathered}$$

Final Answer: X is Sodium hydroxide $\left(\mathrm{NaOH}\right)$ and Y is Hydrochloric acid $\left(\mathrm{HCl}\right)$ .