Question

which of the following is not an indication of a positive test for a particular ion in a solution? a the formation of a precipitate b the evolution of gas c the dissolving of a solid d the solution retains clarity

Explanation:

To determine which is not a positive test indication for an ion:

• Option A: Precipitate formation (e.g., \( \text{Ag}^+ + \text{Cl}^-

ightarrow \text{AgCl}(s) \)) confirms ion presence.

• Option B: Gas evolution (e.g., \( \text{CO}_3^{2-} + 2\text{H}^+

ightarrow \text{CO}_2(g) + \text{H}_2\text{O} \)) confirms ion presence.

• Option C: Dissolving a solid (e.g., \( \text{AgCl} \) dissolving in ammonia for \( \text{Ag}^+ \) test) can confirm ion presence.
• Option D: A solution retaining clarity means no visible reaction (precipitate, gas, or color change) occurred, so it does not indicate a positive test for the ion.

Answer:

D. The solution retains clarity