Redox Reactions · JEE Main previous year questions

The disproportionation of ${\text{MnO}}_4^{2-}$ in acidic medium resulted in the formation of two manganese compounds A and B. If the oxidation state of $\text{Mn}$ in B is smaller than that of A, then the spin-only magnetic moment ($\mu$) value of B in BM is _________. (Nearest integer)

On reaction with stronger oxidizing agent like $\mathrm{KI}{\mathrm{O}}_4$, hydrogen peroxide oxidizes with the evolution of ${\mathrm{O}}_2$. The oxidation number of $\mathrm{I}$ in $\mathrm{KI}{\mathrm{O}}_4$ changes to ____.

Given below are two statements. Statement I : Hydrogen peroxide can act as an oxidizing agent in both acidic and basic conditions. Statement II : Density of hydrogen peroxide at $298\text{ K}$ is lower than that of ${\text{D}}_2\text{O}$. In the light of the above statements, choose the correct answer from the options given below.

1. A.Both Statement I and Statement II are true.
2. B.Both Statement I and Statement II are false.
3. C.Statement I is true but Statement II is false.
4. D.Statement I is false but Statement II is true.

Which of the given reactions is not an example of disproportionation reaction?

1. A.$2{\mathrm{H}}_2{\mathrm{O}}_2\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$
2. B.$2\mathrm{N}{\mathrm{O}}_2+{\mathrm{H}}_2\mathrm{O}\to \mathrm{HN}{\mathrm{O}}_3+\mathrm{HN}{\mathrm{O}}_2$
3. C.$\mathrm{Mn}{\mathrm{O}}_4^{-}+4{\mathrm{H}}^{+}+3{\mathrm{e}}^{-}\to \mathrm{Mn}{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$
4. D.$3\mathrm{Mn}{\mathrm{O}}_4^{2-}+4{\mathrm{H}}^{+}\to 2\mathrm{Mn}{\mathrm{O}}_4^{-}+\mathrm{Mn}{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$

BeO reacts with HF in presence of ammonia to give [A] which on thermal decomposition produces [B] and ammonium fluoride. Oxidation state of Be in [A] is ____________.

Choose the correct stability order of group 13 elements in their + 1 oxidation state :

1. A.Al < Ga < In < Tl
2. B.Tl < In < Ga < Al
3. C.Al < Ga < Tl < In
4. D.Al < Tl < Ga < In

Which one of the following is an example of disproportionation reaction ?

1. A.$3\mathrm{Mn}{\mathrm{O}}_4^{2-}+4{\mathrm{H}}^{+}\to 2\mathrm{Mn}{\mathrm{O}}_4^{-}+\mathrm{Mn}{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$
2. B.$\mathrm{Mn}{\mathrm{O}}_4^{-}+4{\mathrm{H}}^{+}+4e^{-}\to \mathrm{Mn}{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$
3. C.$10{\mathrm{I}}^{-}+2\mathrm{Mn}{\mathrm{O}}_4^{-}+16{\mathrm{H}}^{+}\to 2\mathrm{M}{\mathrm{n}}^{2+}+8{\mathrm{H}}_2\mathrm{O}+5{\mathrm{I}}_2$
4. D.$8\mathrm{Mn}{\mathrm{O}}_4^{-}+3{\mathrm{S}}_2{\mathrm{O}}_3^{2-}+{\mathrm{H}}_2\mathrm{O}\to 8\mathrm{Mn}{\mathrm{O}}_2+6\mathrm{S}{\mathrm{O}}_4^{2-}+2\mathrm{O}{\mathrm{H}}^{-}$

The most common oxidation state of Lanthanoid elements is +3. Which of the following is likely to deviate easily from +3 oxidation state?

1. A.Ce (At. No. 58)
2. B.La (At. No. 57)
3. C.Lu (At. No. 71)
4. D.Gd (At. No. 64)

Among the following, which is the strongest oxidizing agent?

1. A.${\mathrm{Mn}}^{3+}$
2. B.${\mathrm{Fe}}^{3+}$
3. C.${\mathrm{Ti}}^{3+}$
4. D.${\mathrm{Cr}}^{3+}$

Manganese (VI) has ability to disproportionate in acidic solution. The difference in oxidation states of two ions it forms in acidic solution is ____________.

The sum of oxidation states of two silver ions in $[\mathrm{Ag}(\mathrm{N}{\mathrm{H}}_3{)}_2][\mathrm{Ag}(\mathrm{CN}{)}_2]$ complex is ____.

The correct order of following 3d metal oxides, according to their oxidation numbers is : (a) $\mathrm{Cr}{\mathrm{O}}_3$, (b) $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3$, (c) $\mathrm{Mn}{\mathrm{O}}_2$, (d) ${\mathrm{V}}_2{\mathrm{O}}_5$, (e) $\mathrm{C}{\mathrm{u}}_2\mathrm{O}$

1. A.(d) > (a) > (b) > (c) > (e)
2. B.(a) > (c) > (d) > (b) > (e)
3. C.(a) > (d) > (c) > (b) > (e)
4. D.(c) > (a) > (d) > (e) > (b)

Identify the process in which change in the oxidation state is five :

1. A.$\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}\to 2C{\mathrm{r}}^{3+}$
2. B.$\mathrm{Mn}{\mathrm{O}}_4^{-}\to \mathrm{M}{\mathrm{n}}^{2+}$
3. C.$\mathrm{Cr}{\mathrm{O}}_4^{2-}\to \mathrm{C}{\mathrm{r}}^{3+}$
4. D.${\mathrm{C}}_2{\mathrm{O}}_4^{2-}\to 2C{\mathrm{O}}_2$

Which one of the following group-15 hydride is the strongest reducing agent?

1. A.$\mathrm{As}{\mathrm{H}}_3$
2. B.$\mathrm{Bi}{\mathrm{H}}_3$
3. C.$\mathrm{P}{\mathrm{H}}_3$
4. D.$\mathrm{Sb}{\mathrm{H}}_3$

The species given below that does NOT show disproportionation reaction is :

1. A.${\text{BrO}}_4^{-}$
2. B.${\text{BrO}}^{-}$
3. C.${\text{BrO}}_2^{-}$
4. D.${\text{BrO}}_3^{-}$

The oxidation states of nitrogen in $\mathrm{NO},\mathrm{N}{\mathrm{O}}_2,{\mathrm{N}}_2\mathrm{O}$ and $\mathrm{N}{\mathrm{O}}_3^{-}$ are in the order of :

1. A.${\mathrm{N}}_2\mathrm{O}>\mathrm{N}{\mathrm{O}}_2>\mathrm{NO}>\mathrm{N}{\mathrm{O}}_3^{-}$
2. B.$\mathrm{NO}>\mathrm{N}{\mathrm{O}}_2>{\mathrm{N}}_2\mathrm{O}>\mathrm{N}{\mathrm{O}}_3^{-}$
3. C.$\mathrm{N}{\mathrm{O}}_2>\mathrm{N}{\mathrm{O}}_3^{-}>\mathrm{NO}>{\mathrm{N}}_2\mathrm{O}$
4. D.$\mathrm{N}{\mathrm{O}}_3^{-}>\mathrm{N}{\mathrm{O}}_2>\mathrm{NO}>{\mathrm{N}}_2\mathrm{O}$

Given below are two statements : Statement I : ${\mathrm{H}}_2{\mathrm{O}}_2$ can act as both oxidising and reducing agent in basic medium. Statement II : In the hydrogen economy, the energy is transmitted in the form of dihydrogen. In the light of the above statements, choose the correct answer from the options given below :

1. A.Both statement I and statement II are false
2. B.Statement I is false but statement II is true
3. C.Statement I is true but statement II is false
4. D.Both statement I and statement II are true

Match List - I with List - II : $$\begin{array}{llll}& \text{List - I}& & \text{List - II}\\ & \text{Name of oxo acid}& & \text{Oxidation state of ’P’}\\ \text{(a)}& \text{Hypophosphorous acid}& \text{(i)}& +5\\ \text{(b)}& \text{Orthophosphoric acid}& \text{(ii)}& +4\\ \text{(c)}& \text{Hypophosphoric acid}& \text{(iii)}& +3\\ \text{(d)}& \text{Orthophosphorous acid}& \text{(iv)}& +2\\ & & \text{(v)}& +1\end{array}$$ Choose the correct answer from the options given below :

1. A.(a) - (iv), (b) - (v), (c) - (ii), (d) - (iii)
2. B.(a) - (iv), (b) - (i), (c) - (ii), (d) - (iii)
3. C.(a) - (v), (b) - (i), (c) - (ii), (d) - (iii)
4. D.(a) - (v), (b) - (iv), (c) - (ii), (d) - (iii)

Compound A used as a strong oxidizing agent is amphoteric in nature. It is the part of lead storage batteries. Compound A is :

1. A.$\mathrm{PbO}$
2. B.$\mathrm{Pb}{\mathrm{O}}_2$
3. C.$\mathrm{PbS}{\mathrm{O}}_4$
4. D.$\mathrm{P}{\mathrm{b}}_3{\mathrm{O}}_4$

Dichromate ion is treated with base, the oxidation number of Cr in the product formed is ___________.

The lanthanoid that does NOT show +4 oxidation state is :

1. A.Tb
2. B.Dy
3. C.Ce
4. D.Eu

The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are x, y and z. The sum of x, y and z is ____. $\mathrm{N}{\mathrm{a}}_4[\mathrm{Fe}(\mathrm{CN}{)}_5(\mathrm{NOS})]$ (A) $\mathrm{N}{\mathrm{a}}_4[\mathrm{Fe}{\mathrm{O}}_4]$ (B) $[\mathrm{F}{\mathrm{e}}_2(\mathrm{CO}{)}_9]$ (C)

The compound that cannot act both as oxidising and reducing agent is :

1. A.${\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_4$
2. B.${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_3$
3. C.${\mathrm{H}}_2{\mathrm{O}}_2$
4. D.$\mathrm{HN}{\mathrm{O}}_2$

Oxidation number of potassium in ${\mathrm{K}}_2\mathrm{O}$, ${\mathrm{K}}_2{\mathrm{O}}_2$ and $\mathrm{K}{\mathrm{O}}_2$ respectively is :

1. A.+1, +2 and + 4
2. B.+1, +1 and + 1
3. C.+2, +1 and $+\frac{1}{2}$
4. D.+1, +4, and +2

The redox reaction among the following is :

1. A.reaction of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ with $\mathrm{NaOH}$.
2. B.formation of ozone from atmospheric oxygen in the presence of sunlight.
3. C.combination of dinitrogen with dioxygen at 2000 K
4. D.reaction of $[\mathrm{Co}({\mathrm{H}}_2\mathrm{O}{)}_6]\mathrm{C}{\mathrm{l}}_3$ With $\mathrm{AgN}{\mathrm{O}}_3$