Assertion (A): Silver oxide and mercury(II) oxide can be decomposed to the metals simply by heating. Reason (R): The Delta G deg of formation of these oxides becomes positive at moderate temperatures, so their Ellingham lines cross Delta G deg = 0.

Both A and R are true and R is the correct explanation of A

Both A and R are true but R is not the correct explanation of A

JEE Main levelSingle correct optionDifficulty 2 of 3mt203

Assertion (A): Silver oxide and mercury(II) oxide can be decomposed to the metals simply by heating. Reason (R): The $Δ G^{\circ}$ of formation of these oxides becomes positive at moderate temperatures, so their Ellingham lines cross $Δ G^{\circ} = 0$ .

For

2 Ag X_{2} O 4 Ag + O X_{2}

and

2 HgO 2 Hg + O X_{2}

the entropy of decomposition is positive, and once the formation line crosses zero (

Δ G_{f} > 0

) decomposition becomes spontaneous without any reductant. R explains A.