JEE Main · 2019 · 11 Jan 2019 · Shift 1 · s-Block Elements

The amphoteric hydroxide is:

(A)be $(OH)_{2}$ ✓ Correct
(B) $Ca (OH)_{2}$
(C) $Mg (OH)_{2}$
(D) $Sr (OH)_{2}$

Answer: (A)

Solution

Among these group-2 hydroxides the odd one out is beryllium hydroxide. The very small, strongly polarising

Be X^{2 +}

ion gives the

Be - O

bond appreciable covalent character, so

Be (OH) X_{2}

can both donate to an acid and accept from a strong base, dissolving in each. The hydroxides of magnesium, calcium and strontium are simply basic, so the amphoteric one is

Be (OH) X_{2}

JEE Main · 2019 · 11 Jan 2019 · Shift 1 · Single correct option

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