Redox Reactions

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iv) is the correct answer.

Disproportionate reactions are defined as the reactions in which the same substance is oxidized as well as reduced. Here, the below reaction is given as-

2NO₂ + 2OH^- →NO₂ ^-+ NO₃^- +H₂O

In this reaction, N is both oxidized as well as reduced since O.N. of N increases from +4 in NO₃⁻?  to +5 in NO₂ ? and decreases from +4 in NO to +3 in NO₂⁻.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iv) is the correct answer

For 3d¹ 4s² can exhibit the highest oxidation state as 2+1 = +3,

For 3d³4s²can exhibit the highest oxidation state as 2+3 = +5

For 3d⁵4s¹can exhibit the highest oxidation state as 1+5 = +6

For 3d⁵4s²can exhibit the highest oxidation state as 2+5 = +7

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (i) is the correct answer

Let the oxidation number of central atom be 'y'.

Oxidation number of O = −2

CrO₂⁻: y + 2 * (−2) = −1

y − 4 = −1 or y = +3

CrO₄²⁻? : y + 4 * (−2) = −2

y − 8 = −2 or y = +6

ClO₃⁻: y + 3 * (−2) = −1

y − 6 = −1 or y = +5

MnO₄⁻: y + 4 * (−2) = −1

y − 8 = −1 or y = +7

increasing order of oxidation number of the central atom is:

CrO₂ ^– , ClO₃ ^–, CrO₄ ^2–, MnO₄

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (ii) is the correct answer.

The oxidation states are given below-

In NH₂OH oxidation of N is -1.

NH₄NO₃ exists as NH₄⁺.NO₃^-,    

Thus, the oxidation state of N in NH₄⁺ is -3 while in NO₃^? is +5.

In N₂H₄ oxidation of N is -2

In N₃H oxidation of N is $\frac{-1}{3}$

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (i) is the correct answer

In ionic hydrides hydrogen exists in -1 oxidation state because the hydrogen acquires negative charge in the presence of its companion.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (i) is the correct answer.

Standard reduction potential of bromine is higher than Iodine, hence Bromine is a stronger oxidant than iodine.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iv) is the correct answer.

E? will be negative for the pair Ag and Fe³⁺. Hence the reaction is not feasible.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iv) is the correct answer

Reduction potential is defined as the tendency of the specie to get reduced. More positive the value of E® , greater is the tendency of the species to get reduced and stronger is the oxidising agent. 

On the basis of the given E®  values, the order of getting reduced is:

Br₂Ag + I₂Cu²⁺

Hence, Cu has the least tendency to get reduced and will itself gets oxidise and reduce other species as: Br₂? , Ag⁺ and I₂.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iv) is the correct answer

The strongest oxidising agent means it has greater tendency to oxidise other species and itself gets easily reduced. So higher the E^? values, stronger is the oxidising agent it is. Thus, Ag⁺ having the highest positive E^?   value among the given systems, is the strongest oxidising agent.