For the given redox reaction, 
\(\mathrm{{a} {Cr}_2 {O}_7^{2-}+{bSO}_3^{2-}({aq})+{c} {H}^{+}({aq})} →\)
\(\mathrm{2 {a} {Cr}^{3+}({aq})+{bSO}_4^{2-}({aq})+\frac{{c}}{2} {H}_2 {O}(\ell)} \)
the coefficients a, b and c of a  balanced equation are found to be, respectively:
1. 8, 1, 3 
2. 1, 3, 8 
3. 3, 8, 1 
4. 1, 8, 3
Subtopic:  Balancing of Equations |
 77%
From NCERT
NEET - 2023
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Identify the incorrect statement from the following:
1. Lithium is the strongest reducing agent among the alkali metals.
2. Alkali metals react with water to form their hydroxides.
3. The oxidation number of K in KO2 is +4.
4. Ionisation enthalpy of alkali metals decreases from top to bottom in the group.
Subtopic:  Introduction to Redox and Oxidation Number |
 65%
From NCERT
NEET - 2022
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At \(298 {~K},\) the standard electrode potentials of \(\mathrm{{Cu}^{2+} /{Cu},}\) \(\mathrm{{Zn}^{2+} / {Zn},~~ {Fe}^{2+} / {Fe}}\) and \(\mathrm{{Ag}^{+} / {Ag}} \) are \(\mathrm{0.34 {~V}, -0.76 {~V},}\)  \(\mathrm{-0.44 {~V}}\) and \(\mathrm{0.80 {~V},}\) respectively.
On the basis of standard electrode potentials, predict which of the following reaction can not occur?
1. \(\mathrm{2 {CuSO}_{4}({aq})+2 {Ag}({s}) → 2 {Cu}({s})+{Ag}_{2} {SO}_{4}({aq})} \)
2. \(\mathrm{{CuSO}_{4}({aq})+{Zn}({s})} \) \(\mathrm{→ {ZnSO}_{4}({aq})+{Cu}({s})} \)
3. \(\mathrm{{CuSO}_{4}({aq})+{Fe}({s})} \) \(\mathrm{→ {FeSO}_{4}({aq})+{Cu}({s})} \)
4. \(\mathrm{{FeSO}_{4}({aq})+{Zn}({s})} \) \(→ \mathrm{{ZnSO}_{4}({aq})+{Fe}({s})} \)
Subtopic:  Emf & Electrode Potential |
 69%
From NCERT
NEET - 2022
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A set of species capable of showing disproportionation reactions is:

1. \(\mathrm{ClO^–_2, ~ClO^–_3,~ ClO^–_4, ~Cl_2}\)
2. \(\mathrm{Cl_2, ~ClO^–_2, ~ClO^–_3, ~S_8}\)
3. \(\mathrm{ClO^–_4, ~ClO^–, ~ClO^–_2, ~F_2}\)
4. \(\mathrm{ClO^–_3, ~ClO^–_4, ~H_2O_2, ~ClO^–}\)
Subtopic:  Redox Titration & Type of Redox |
 62%
From NCERT
NEET - 2022
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Which of the following reactions is a decomposition redox reaction?
1. \(\mathrm{2 {Pb}\left({NO}_3\right)_2({s}) \rightarrow 2 {PbO}({s})+4 {NO}_2({g})+{O}_2({g})} \)
2. \(\mathrm{{N}_2({g})+{O}_2({g}) \rightarrow 2 {NO}({g})} \)
3. \(\small{\mathrm{{Cl}_2({g})+2 {OH}^{-}({aq}) \rightarrow {ClO}^{-}({aq})+{Cl}^{-}({aq})+4 {H}_2 {O}(\ell)}}\)
4. \(\small{\mathrm{{P}_4({s})+3 {OH}^{-}({aq})+3 {H}_2 {O}(\ell) \rightarrow{PH}_3({g})+3 {H}_2 {PO}_2^{-}({aq})}}\)
Subtopic:  Redox Titration & Type of Redox |
 72%
From NCERT
NEET - 2022
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The correct example of metal displacement reaction among the following is:

1. Fe+2HClFeCl2+H2

2. 2Pb(NO3)22PbO+4NO2+O2

3. 2KClO32KCl+3O2

4. Cr2O3+2AlAl2O3+2Cr

Subtopic:  Introduction to Redox and Oxidation Number |
 70%
From NCERT
NEET - 2021
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What is the alteration in the oxidation state of carbon in the given reaction?

\(\mathrm{{CH_4}_{(g)} + 4{Cl_2}_{(g)} \rightarrow {CCl_4}_{(l)} + 4 HCl_{(g)}}\)

1. 0 to +4 2. –4 to +4
3. 0 to –4 4. +4 to +4
Subtopic:  Oxidizing & Reducing Agents |
 83%
From NCERT
NEET - 2020
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The incorrect oxidation number of the underlined atom in the following species is:

1. Cu2O is -1 2. Cl\(O_{3}^{-}\) is +5
3. K2Cr2O7 is +6 4. HAuCl4  is +3
Subtopic:  Oxidizing & Reducing Agents |
 80%
From NCERT
NEET - 2020
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From the following, identify the reaction having the top position in the EMF series (standard reduction potential) according to their electrode potential at 298 K.

1. Mg2++ 2eMg(s)
2. Fe2+ + 2e Fe(s)
3. Au3++ 3eAu(s)
4. K++ le K(s)

Subtopic:  Application of Electrode Potential |
From NCERT
NEET - 2020
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Disproportionation reactions are:

(a) 2Cu+  Cu2++Cu0

(b) 3MnO42-+4H+  2MnO4-+MnO2+2H2O

(c) 2KMnO4  K2MnO4+MnO2+O2

(d) 2MnO4-+3Mn2++2H2O  5MnO2+4H

1. (a) and (d) only

2. (a) and (b) only

3. (a), (b) and (c)

4. (a), (c) and (d)

Subtopic:  Introduction to Redox and Oxidation Number |
 60%
From NCERT
NEET - 2019
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