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JEE Main 20204 SeptemberMorning Shift

Exam: JEE Main
Year: 2020
Date: 4 September
Shift: Morning Shift
Subject: Chemistry
Chapter: s Block Elements

JEE Main 2020 · 4 September · Morning Shift · Chemistry · s Block Elements

On combustion of Li, Na and K in excess of air, the major oxides...

On combustion of

Li, Na

and

K

in excess of air, the major oxides formed, respectively, are:

Options

A ${Li}_{2}{O}_{2}, {Na}_{2}O$ and ${K}_{2}{O}_{2}$
B ${Li}_{2}O, {Na}_{2}{O}_{2}$ and ${KO}_{2}$
C ${Li}_{2}O, {Na}_{2}O$ and ${K}_{2}{O}_{2}$
D ${Li}_{2}O, {Na}_{2}{O}_{2}$ and ${K}_{2}O$

Correct answer

B. ${Li}_{2}O, {Na}_{2}{O}_{2}$ and ${KO}_{2}$

Step-by-step solution

On heating in excess air

Li

form oxide sodium form peroxide while

K

,

Rb

,

Cs

form superoxide.

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