Assertion (A): The decomposition of hydrogen peroxide to form water and oxygen is an
example of disproportionation reaction.
Reason (R) : The oxygen of peroxide is in -1 oxidation state and it is converted to zero ox
idation state in O2 and -2 oxidation state in H2O.
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Both A and R is true and R is the correct explanation of A.
(ii) Both A and R is true but R is not the correct explanation of A.
(iii) A is true but Ris false.
(iv) Both A and R is false
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Answers
=> A disproportionation reaction is a decomposition reaction where the main element in the compound is found to be both reduced and oxidized at the same time.
=> The equation for the reaction is: 2H2O2 -------> 2H2O + O2
=> Here, 2 products are formed: H2O and O2.
=> We know that the oxidation state in O2 is zero .
=> Let the oxidation states of O in H2O2 and H2O be x and y respectively.
=> Now, 2*1 + 2*x = 0 => 2x = -2 => x = -2/2 => x = -1
=> 2*1 + y = 0 => y = -2
=> So, the oxidation state in H2O2 is -1 and that in water is -2.
=> Indeed, the oxidation state of O changes from -1 in H2O2 to -2 in water (reduced) and -1 in H2O2 to zero in water (oxidized).
=> It is indeed a Disproportionation Reaction.
=> Hence, both A and R are true and R is the correct explanation of A.
Answer:
Both assertion and reason are correct and reason is correct explanation of assertion.