JEE Advanced 2020 · Paper 1 · Chemistry Q2

ChemistrySingle correct+3 / -1Question 20 of 54

Which of the following liberates $\ce{O2}$ upon hydrolysis?

\ce{Pb3O4}

\ce{KO2}

\ce{Na2O2}

\ce{Li2O2}

Answer and worked solution

Official answer: B

$\ce{KO2}$ is a superoxide. With water it gives oxygen: $\ce{4KO2 + 2H2O -> 4KOH + 3O2}$ .
$\ce{Na2O2}$ and $\ce{Li2O2}$ are peroxides. Hydrolysis gives $\ce{H2O2}$ (e.g. $\ce{Na2O2 + 2H2O -> 2NaOH + H2O2}$ ), not $\ce{O2}$ .
$\ce{Pb3O4}$ is not hydrolysed by water.

(B)

Topics:Important compounds of s-block

JEE Advanced 2020 · Paper 1, Chemistry question 2