When excess of `NaOH` solution is added in potash alum the product is.

Options

A. a bluish precipitate
B. clear solution
C. white precipitate
D. greenish precipitate

Answer

B

Explanation

Potash alum is `K_(2)SO_(4)Al_(2)(SO_(4))_(3) cdot 24H_(2)O`.
`Al_(2)(SO_(4))_(3)` reacts with NaOH to form `NaAlO_(2)` which is soluble. `K_(2)SO_(4) and Na_(2)SO_(4)` are also soluble and thus a clear solution is obtained in water.
`Al_(2)(SO_(4))_(3)+6NaOH rarr 2 Al(OH)_(3) +3Na_(2)SO_(4)`
`Al(OH)_(3)+NaOH rarr underset("Soluble")NaAlO_(2) +2H_(2)O`