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Q. No.For the given redox reaction, find out the coefficients a, b and c of a balanced equation respectively:
\(\mathrm{{a} {Cr}_2 {O}_7^{2-}+{bSO}_3^{2-}({aq})+{c} {H}^{+}({aq})} →\)\(\mathrm{2 {a} {Cr}^{3+}({aq})+{bSO}_4^{2-}({aq})+\frac{{c}}{2} {H}_2 {O}(\ell)} \)
\(\mathrm{{a} {Cr}_2 {O}_7^{2-}+{bSO}_3^{2-}({aq})+{c} {H}^{+}({aq})} →\)\(\mathrm{2 {a} {Cr}^{3+}({aq})+{bSO}_4^{2-}({aq})+\frac{{c}}{2} {H}_2 {O}(\ell)} \)
| 1. | 8, 1 and 3 | 2. | 1, 3 and 8 |
| 3. | 3, 8 and 1 | 4. | 1, 8 and 3 |
Subtopic: Balancing of Equations |
77%
Level 2: 60%+
NEET - 2023
Hints
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 |
66%
Level 2: 60%+
NEET - 2022
Hints
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?
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%
Level 2: 60%+
NEET - 2022
Hints
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%
Level 2: 60%+
NEET - 2022
Hints
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 |
73%
Level 2: 60%+
NEET - 2022
Hints
The correct example of metal displacement reaction among the following is:
| 1. | \(\mathrm{Fe}+2 \mathrm{HCl} \rightarrow \mathrm{FeCl}_2+\mathrm{H}_2 \uparrow \) |
| 2. | \(2 \mathrm{~Pb}\left(\mathrm{NO}_3\right)_2 \rightarrow 2 \mathrm{PbO}+4 \mathrm{NO}_2+\mathrm{O}_2 \uparrow \) |
| 3. | \( 2\text {KClO}_3 \xrightarrow {\Delta}2 \text {KCl} + 3 \text O_2 \) |
| 4. | \(\mathrm{Cr}_2 \mathrm{O}_3+2 \mathrm{Al} \xrightarrow {\Delta} \mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{Cr}\) |
Subtopic: Introduction to Redox and Oxidation Number |
70%
Level 2: 60%+
NEET - 2021
Hints
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%
Level 1: 80%+
NEET - 2020
Hints
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: Introduction to Redox and Oxidation Number |
81%
Level 1: 80%+
NEET - 2020
Hints
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++ 2e– → Mg(s) | 2. | Fe2+ + 2e– → Fe(s) |
| 3. | Au3++ 3e– → Au(s) | 4. | K++ 1e – → K(s) |
Subtopic: Application of Electrode Potential |
Level 3: 35%-60%
NEET - 2020
Hints
Disproportionation reactions are:
| (a) | |
| (b) | |
| (c) | |
| (d) |
| 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 |
61%
Level 2: 60%+
NEET - 2019
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