JEE Main · 2020 · 08 Jan 2020 · Shift 2 · s-Block Elements

A metal (A) on heating in nitrogen gas gives compound B. B on treatment with

H_{2} O

gives a colourless gas which when passed through

CuSO_{4}

solution gives a dark blue-violet coloured solution. A and B respectively, are:

(A)Mg and $Mg (NO_{3})_{2}$
(B)Na and $NaNO_{3}$
(C)Mg and $Mg_{3} N_{2}$ ✓ Correct
(D)Na and $Na_{3} N$

Answer: (C)

Solution

A metal that burns in nitrogen to a nitride, whose nitride then reacts with water to release a gas that turns copper sulphate solution deep blue, points to magnesium. Magnesium burns as

3 Mg + N X_{2} Mg X_{3} N X_{2}

, and the nitride hydrolyses,

Mg X_{3} N X_{2} + 6 H X_{2} O 3 Mg (OH) X_{2} + 2 NH X_{3}

; the ammonia then forms the deep blue-violet

[Cu (NH X_{3}) X_{4}] X^{2 +}

with

CuSO X_{4}

. So

A

Mg

and

B

Mg X_{3} N X_{2}

JEE Main · 2020 · 08 Jan 2020 · Shift 2 · Single correct option

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JEE Main · 2020 · 08 Jan 2020 · Shift 2 · s-Block Elements

Solution

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