An unknown mixture contains one or two of the following: `CaCO_(3),BaCl_(2),AgNO_(3),Na_(2)SO_(4),ZnSO_(4) and NaOH`. The mixture is completely soluble in water and solution gives pink colour with phenolphthalein. When dilute hydrochloric acid is gradually added to the solution, a precipitate is formed which dissolved with further addition of the acid.
Q. Which of the following combination of compounds is soluble in water?

Options

A. `BaCl_(2) and AgNO_(3)`
B. `AgNO_(3) and NaOH`
C. `BaCl_(2) and Na_(2)SO_(4)`
D. `ZnSO_(4) and` excess `NaOH`

Answer

D

Explanation

Mixture contains `NaOH+ZnSO_(4)`
`NaOH+ZnSO_(4) to underset("soluble")(Na_(2)ZnO_(2))+Na_(2)SO_(4)+2H_(2)O`
`Na_(2)ZnO_(2)+2HCl to 2NaCl+Zn(OH)_(2)darr`
`Zn(OH)_(2)+2HCl to underset("soluble")(ZnCl_(2))+2H_(2)O`