Redox Reactions · JEE Main previous year questions

2021 10 questions

1. Q832021 · 1 Sept 2021 · Shift 2· Numerical answer

   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 ____.

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   Answer: 2

2. Q722021 · 25 Jul 2021 · Shift 1

   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)
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   Answer: C

3. Q742021 · 25 Jul 2021 · Shift 2

   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.${\mathrm{C}}_2{\mathrm{O}}_4^{2-}\to 2C{\mathrm{O}}_2$
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   Answer: B

4. Q682021 · 22 Jul 2021 · Shift 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.$\mathrm{Sb}{\mathrm{H}}_3$
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   Answer: B

5. Q642021 · 20 Jul 2021 · Shift 1

   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.${\text{BrO}}_3^{-}$
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   Answer: A

6. Q702021 · 18 Mar 2021 · Shift 2

   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.$\mathrm{N}{\mathrm{O}}_3^{-}>\mathrm{N}{\mathrm{O}}_2>\mathrm{NO}>{\mathrm{N}}_2\mathrm{O}$
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   Answer: D

7. Q772021 · 16 Mar 2021 · Shift 1

   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
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   Answer: D

8. Q782021 · 16 Mar 2021 · Shift 1

   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)
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   Answer: C

9. Q692021 · 26 Feb 2021 · Shift 1

   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.$\mathrm{P}{\mathrm{b}}_3{\mathrm{O}}_4$
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   Answer: B

10. Q832021 · 26 Feb 2021 · Shift 1· Numerical answer

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

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    Answer: 6