Option (iii) is the correct answer. The assertion is true because molten ionic compounds conduct electricity, but the reason is completely false because ions are fixed in solids and mobile only in liquids.
Assertion (A): Copper sulfate conducts electricity in the molten state but not in the solid state. Reason (R): Copper and sulfate ions are fixed in the lattice in molten state, while in solid state they can move freely. Choose the correct option: (i) Both A and R are true and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true.
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Option (iii) is correct. Assertion A is true because copper sulfate is an ionic compound whose ions become free to move and conduct electricity when melted. Reason R is completely false because ions are tightly held in fixed positions within the solid crystal lattice, whereas they become mobile only in the molten state or aqueous solution to conduct electric current.
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