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JEE Main 201912 JanuaryMorning Shift

Exam: JEE Main
Year: 2019
Date: 12 January
Shift: Morning Shift
Subject: Chemistry
Chapter: s Block Elements

JEE Main 2019 · 12 January · Morning Shift · Chemistry · s Block Elements

A metal on combustion in excess air forms X . X upon hydrolysis...

A metal on combustion in excess air forms

X

.

X

upon hydrolysis with water yields

{H}_{2}{O}_{2}

and

{O}_{2}

along with another product. The metal is:

Options

A $Na$
B $Mg$
C $Li$
D $Rb$

Correct answer

D. $Rb$

Step-by-step solution

K, Rb

and

Cs

form super oxides on reaction with excess air

Rb + {O}_{2} \to Rb{O}_{2}

(excess)

2Rb{O}_{2} + 2{H}_{2}O \to 2RbOH + {H}_{2}{O}_{2} + {O}_{2} ↑

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