Assertion (A): The colour of old lead paintin | vedclass

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(C) Old lead paintings often turn black due to the formation of lead sulfide $(PbS)$ by the reaction of lead pigments with atmospheric $H_2S$.The colo

Vedclass · Accepted Answer

$A$ is true,$R$ is false

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(C) Old lead paintings often turn black due to the formation of lead sulfide $(PbS)$ by the reaction of lead pigments with atmospheric $H_2S$.The colour is restored by washing with $H_2O_2$,which oxidizes the black $PbS$ to white lead sulfate $(PbSO_4)$.The reaction is: $PbS(s) + 4H_2O_2(aq) \rightarrow PbSO_4(s) + 4H_2O(l)$.In this reaction,$H_2O_2$ acts as an oxidizing agent,not a reducing agent.Therefore,Assertion $(A)$ is true,but Reason $(R)$ is false.

Assertion $(A)$: The colour of old lead paintings can be restored by washing them with a dilute solution of $H_2O_2$.
Reason $(R)$: Hydrogen peroxide reduces $PbS$ to $Pb$.

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Assertion $(A)$: The colour of old lead paintings can be restored by washing them with a dilute solution of $H_2O_2$.Reason $(R)$: Hydrogen peroxide reduces $PbS$ to $Pb$.