Question

A compound was found to be soluble in water. It was also found that addition of acid to an aqueous solution of this compound resulted in the formation of carbon dioxide. Which one of the following cations would form a precipitate when added to an aqueous solution of this compound?

Answer 1

A compound was found to be soluble in water. It was also found that addition of acid to an aqueous solution of this compound resulted in the formation of carbon dioxide. Which one of the following cations would form a precipitate when added to an aqueous solution of this compound?

Options

a. NH4

b. K

c. Cr

d. Rb

e. Na

Answer: c: Cr

Explanation:

The aforementioned reaction are banters for to distract ones focus from the question.

However it should be noted that

Cr can be found in tannery waste water showing that it can be soluble in water.

The carbonate compound when reacting with acid CO_2 evolves.

Focusing on the cation that would form a precipitate when added to an aqueous solution.

Chemical precipitation method is a common method for to remove chromium and to recover it from  tannery wastewater.

Cr would form a precipitate.