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KCET · Chemistry · Practical Chemistry

When salt BA is treated with Conc. \(\text{H}_2\text{SO}_4\) reddish brown gas is liberated. The aqueous solution of BA gives pale yellow precipitate with \(\text{AgNO}_3\) solution. Which of the following anion (\(\text{A}^-\)) is present in the salt BA?

  1. A \(\text{Cl}^-\)
  2. B \(\text{CO}_3^{2-}\)
  3. C \(\text{SO}_4^{2-}\)
  4. D \(\text{Br}^-\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\text{Br}^-\)

Step-by-step Solution

Detailed explanation

When a salt containing bromide ion (\(\text{Br}^-\)) is treated with concentrated \(\text{H}_2\text{SO}_4\), reddish-brown bromine gas (\(\text{Br}_2\)) is evolved due to the oxidation of bromide ions by sulphuric acid.

The reaction is: \(2\text{Br}^- + 2\text{H}_2\text{SO}_4 \rightarrow \text{Br}_2 \uparrow + \text{SO}_2 + \text{SO}_4^{2-} + 2\text{H}_2\text{O}\).

When an aqueous solution of a bromide salt is treated with \(\text{AgNO}_3\) solution, a pale yellow precipitate of silver bromide (\(\text{AgBr}\)) is formed.

The reaction is: \(\text{Br}^- + \text{Ag}^+ \rightarrow \text{AgBr} \downarrow\).

Therefore, the anion \(\text{A}^-\) present in the salt BA is \(\text{Br}^-\).

Answer: \(\text{Br}^-\)