MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

According to the Hardy-Schulze rule, the coagulating power of an ion is directly proportional to the magnitude of its charge. Since the ferric oxide sol is positively charged, the anions of the added electrolyte are responsible for its coagulation. The anions provided by the given electrolytes are: KNO _3 NO _3^ - (charge magnitude = 1) K _2 SO _4 SO _4^ 2- (charge magnitude = 2) K _3 PO _4 PO _4^ 3- (charge magnitude = 3) K _4[ Fe(CN) _6] [ Fe(CN) _6]^ 4- (charge magnitude = 4) The order of coagulating power is [ Fe(CN) _6]^ 4- > PO _4^ 3- > SO _4^ 2- > NO _3^ - . Thus, KNO _3 exhibits the minimum coagulating power. Answer: KNO _3