NEET2015ChemistrySurface ChemistryActual
Assertion: Fe ³⁺ can be used for coagulation of As ₂ ~S ₃ sol. Reason: Fe ³⁺ reacts with As ₂ ~S ₃ to give Fe ₂ ~S ₃ .
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion.
- BIfboth assertion and reason are true but reason is not the correct explanation of assertion.
- CIf assertion is true but reason is false.
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false.
Step-by-step solution
Fe ³⁺ is positively charged whereas As ₂ ~S ₃ is negatively charged sol. Their charges are neutralised on mixing hence, mutual precipitation (coagulation) occurs.