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JEE CHEMISTRY MCQ: REDOX REACTIONS

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Given below are two statements.
One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) Aluminium is extracted from bauxite by the electrolysis of molten mixture of

A{l_2}{O_3}

with cryolite.
Reason (R) The oxidation state of

Al

in cryolite is +3.
In the light of the above statements, choose the most appropriate answer from the options given below.

View answer and explanation

Correct option: D

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

The correct answer is D (Both (A) and (R) are true but (R) is not the correct explanation of (A)) because both the assertion and reason are true, but the reason doesn't explain the assertion.

More Questions from REDOX REACTIONS

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The oxidation number of

\mathrm{H}

in sodium hydride is A reagent, which can decrease the oxidation number of an element, is called Consider the following decomposition reaction

2 \mathrm{KClO}_3 \longrightarrow 2 \mathrm{KCl}+3 \mathrm{O}_2

In the above reaction, Assertion (A):

\mathrm{HNO}_3

acts as oxidizing agent.

Reason (R): Oxidation no. of nitrogen is +5, no increase in oxidation no. beyond +5 can occur. The oxidation no. of

\mathrm{HNO}_3

can only decrease. Assertion :- Bromide ion is serving as a reducing agent in the reaction.

\mathrm{MnO}_4^{-}(\mathrm{aq})+\mathrm{Br}^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O} \longrightarrow 2 \mathrm{MnO}_2(\mathrm{aq})+\mathrm{BrO}_3^{-}(\mathrm{aq})+2 \mathrm{OH}^{-}(\mathrm{aq})

Reason :- Oxidation number of

\mathrm{Br}

-1

+5.

A substance, that by its sharp colour change indicates the completion of reaction is known as :