JEE CHEMISTRY MCQ: P-BLOCK ELEMENTS

1 Medium

1 of 1

Understanding +4 | -1

Assertion (A): To initiate the reaction between

\mathrm{O}_2

and a metal, some external heating is required.

Reason (R): Bond dissociation enthalpy of

\mathrm{O}=\mathrm{O}

bond is high

\left(493.4 \mathrm{~kJ} \mathrm{~mol}^{-1}\right)

View answer and explanation

Correct option: A

Both

\mathrm{A}

and

\mathrm{R}

are correct;

\mathrm{R}

is the correct explanation of

A

Option A is correct because the high bond dissociation enthalpy of O=O requires initial energy input to start the reaction, even though the reaction is exothermic overall.

More Questions from P-BLOCK ELEMENTS

Practice All Chapter MCQs →

The gas used for inflating the tyres of aeroplanes is: Which of the following is correct stability order of oxides of

17^{\text {th }}

group elements is: Assertion: Ozone is a powerful oxidising agent in comparison to

{O}_2

.

Reason: Ozone is diamagnetic but

{O}_2

is paramagnetic. Which of the following is kept in water?

\mathrm{C}{\mathrm{N}^ - }

ion and

{\mathrm{N}_2}

are isoelectronic but in contrast to

\mathrm{C}{\mathrm{N}^ - },\mathrm{\;}{\mathrm{N}_2}

is chemically inert because of: Consider the following statements

(i) Reaction

2 {Fe}^{3+}+{SO}_2+2 {H}_2 {O} \rightarrow 2 {Fe}^{2+}+{SO}_4^{2-}+4 {H}^{+}

shows reducing character of sulphur dioxide

(ii)

{H}_2 {~S}_2 {O}_8

contains four

{S}={O}

, two

{S}-{OH}

and one

{O}-

{O}

bond

(iii)

{NH}_3

gas can be dried effectively by using conc.

{H}_2 {SO}_4

.

(iv) One of the major use of

{H}_2 {SO}_4

is in the manufacture of fertilizers.

Which of the following is the correct code for the statements above?