IIT-JEE 2007 · Paper 2 · Chemistry Q32

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ChemistryAssertion and reason+3 / -1Question 32 of 66

STATEMENT-1: Alkali metals dissolve in liquid ammonia to give blue solutions.

because

STATEMENT-2: Alkali metals in liquid ammonia give solvated species of the type $\ce{[M(NH3)_n]+}$ (M = alkali metals).

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1

Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1

Statement-1 is True, Statement-2 is False

Statement-1 is False, Statement-2 is True

Answer and worked solution

Official answer: B

Statement 1. Dilute solutions of alkali metals in liquid ammonia are blue. True.

Statement 2. The metal does form ammoniated cations $\ce{[M(NH3)_n]+}$ . True, but the blue colour comes from the ammoniated electrons $\ce{e-(NH3)_n}$ , not from the cations:
$\ce{M + (x+y)NH3 -> [M(NH3)_x]+ + [e(NH3)_y]-}.$

(B)

Topics:Alkali metals

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IIT-JEE 2007 · Paper 2, Chemistry question 32