Redox Reactions · JEE Main previous year questions

Consider $|x|$ is the difference in oxidation states of $\mathrm{Mn}$ in highest manganese fluoride and highest manganese oxide. The ions with $|x|$ number of unpaired electrons from the following are: A. $\mathrm{S}{\mathrm{c}}^{3+}$ B. $\mathrm{Z}{\mathrm{n}}^{2+}$ C. ${\mathrm{V}}^{2+}$ D. $\mathrm{F}{\mathrm{e}}^{2+}$ E. $\mathrm{C}{\mathrm{o}}^{2+}$ Choose the correct answer from the options given below:

1. A.A and B Only
2. B.C, D and E Only
3. C.C and E Only
4. D.B and E Only

Given below are two statements : Statement (I) : Oxidising power of halogens decreases in the order ${\mathrm{F}}_2>\mathrm{C}{\mathrm{l}}_2>\mathrm{B}{\mathrm{r}}_2>{\mathrm{I}}_2$, which is the basis of "Layer test". Statement (II) : "Layer test" to identify $\mathrm{B}{\mathrm{r}}_2$ and ${\mathrm{I}}_2$ in aqueous solution involves the oxidation of bromide or iodide into $\mathrm{B}{\mathrm{r}}_2$ or ${\mathrm{I}}_2$ respectively with $\mathrm{C}{\mathrm{l}}_2$, which is a type of displacement redox reaction. 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

Given below are two statements : Statement I : The number of pairs, from the following, in which both the ions are coloured in aqueous solution is 3. $[\mathrm{S}{\mathrm{c}}^{3+},\mathrm{T}{\mathrm{i}}^{3+}]$, $[\mathrm{M}{\mathrm{n}}^{2+},\mathrm{C}{\mathrm{r}}^{2+}]$, $[\mathrm{C}{\mathrm{u}}^{2+},\mathrm{Z}{\mathrm{n}}^{2+}]$ and $[\mathrm{N}{\mathrm{i}}^{2+},\mathrm{T}{\mathrm{i}}^{4+}]$ Statement II : $\mathrm{T}{\mathrm{h}}^{4+}$ is the strongest reducing agent among $\mathrm{T}{\mathrm{h}}^{4+}$, $\mathrm{C}{\mathrm{e}}^{4+}$, $\mathrm{G}{\mathrm{d}}^{3+}$ and $\mathrm{E}{\mathrm{u}}^{2+}$. In the light of the above statements, choose the correct answer from the options given below

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

Consider the following reactions ${\text{Na}}_2{\text{B}}_4{\text{O}}_7\stackrel{\Delta }{\to }2X+Y$ ${\text{CuSO}}_4+Y\stackrel{\text{Non-Luminous flame}}{\to }Z+S{O}_3$ $2Z+2X+\text{Carbon}\stackrel{\text{Luminous flame}}{\to }2Q+{\text{Na}}_2{\text{B}}_4{\text{O}}_7+CO$ The oxidation states of Cu in Z and Q, respectively are :

1. A.+2 and +1
2. B.+1 and +1
3. C.+1 and +2
4. D.+2 and +2

The oxidation state of chromium in the final product formed in the reaction between KI and acidified ${\text{K}}_2{\text{Cr}}_2{\text{O}}_7$ solution is :

1. A.+2
2. B.+3
3. C.+4
4. D.+6

Consider the following reactions : $\mathrm{NaCl}+{\mathrm{K}}_2\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7+{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4\to \mathrm{A}+\mathrm{KHS}{\mathrm{O}}_4+\mathrm{NaHS}{\mathrm{O}}_4+{\mathrm{H}}_2\mathrm{O}$ $\mathrm{A}+\mathrm{NaOH}\to \mathrm{B}+\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}$ $\mathrm{B}+{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4+{\mathrm{H}}_2{\mathrm{O}}_2\to \mathrm{C}+\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4+{\mathrm{H}}_2\mathrm{O}$ In the product ' $C^{\prime }$, ' $X$ ' is the number of $O_2^{2-}$ units, ' $Y$ ' is the total number of oxygen atoms present and ' $Z$ ' is the oxidation state of $Cr$. The value of $X+Y+Z$ is ____.

On heating a mixture of common salt and $K_{2}C{r}_2{O}_7$ in equal amount along with concentrated $H_{2}S{O}_4$ in a test tube, a gas is evolved. Formula of the gas evolved and oxidation state of the central metal atom in the gas respectively are:

1. A.$C{r}_2{O}_{2}C{l}_2$ and +3
2. B.$C{r}_2{O}_{2}C{l}_2$ and +6
3. C.$Cr{O}_{2}C{l}_2$ and +6
4. D.$Cr{O}_{2}C{l}_2$ and +5

Given below are some of the statements about Mn and $\mathrm{M}{\mathrm{n}}_2{\mathrm{O}}_7$. Identify the correct statements. A. Mn forms the oxide $\mathrm{M}{\mathrm{n}}_2{\mathrm{O}}_7$, in which Mn is in its highest oxidation state. B. Oxygen stabilizes the Mn in higher oxidation states by forming multiple bonds with Mn. C. $\mathrm{M}{\mathrm{n}}_2{\mathrm{O}}_7$ is an ionic oxide. D. The structure of $\mathrm{M}{\mathrm{n}}_2{\mathrm{O}}_7$ consists of one bridged oxygen. Choose the correct answer from the options given below :

1. A.A, B, C and D
2. B.A, B and D Only
3. C.A, B and C Only
4. D.A, C and D Only

$\mathrm{KMn}{\mathrm{O}}_4$ acts as an oxidising agent in acidic medium. ' X ' is the difference between the oxidation states of Mn in reactant and product. ' Y ' is the number of ' d ' electrons present in the brown red precipitate formed at the end of the acetate ion test with neutral ferric chloride. The value of $\mathrm{X}+\mathrm{Y}$ is ____.

Given below are two statements : Statement I : The N - N single bond is weaker and longer than that of P - P single bond. Statement II : Compounds of group 15 elements in +3 oxidation states readily undergo disproportionation reactions. In the light of the above statements, choose the correct answer from the options given below

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

Given below are two statements: Statement I : ${\mathrm{CrO}}_3$ is a stronger oxidizing agent than ${\mathrm{MoO}}_3$ Statement II : $\mathrm{Cr}(\mathrm{VI})$ is more stable than $\mathrm{Mo}(\mathrm{VI})$ In the light of the above statements, choose the correct answer from the options given below

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

Consider the following elements $\mathrm{In},\mathrm{Tl},\mathrm{Al},\mathrm{Pb},\mathrm{Sn}$ and $\mathrm{Ge}$ . The most stable oxidation states of elements with highest and lowest first ionisation enthalpies, respectively, are

1. A.$+4$ and $+1$
2. B.$+4$ and $+3$
3. C.$+1$ and $+4$
4. D.$+2$ and $+3$

Match the List - I with List - II $$\begin{array}{llll}& \text{List - I}& & \text{List - II}\\ & \text{(Redox Reaction)}& & \text{(Type of Redox Reaction)}\\ \text{(A)}& \mathrm{C}{\mathrm{H}}_{4(\mathrm{g})}+2{\mathrm{O}}_{2(\mathrm{g})}\stackrel{\mathrm{\Delta }}{\to }\mathrm{C}{\mathrm{O}}_{2(\mathrm{g})}+2{\mathrm{H}}_2{\mathrm{O}}_{(\mathrm{l})}& \text{(I)}& \text{Disproportionation reaction}\\ \text{(B)}& 2Na{\mathrm{H}}_{(\mathrm{s})}\stackrel{\mathrm{\Delta }}{\to }2N{\mathrm{a}}_{(\mathrm{s})}+{\mathrm{H}}_{2(\mathrm{g})}& \text{(II)}& \text{Combination reaction}\\ \text{(C)}& {\mathrm{V}}_2{\mathrm{O}}_{5(\mathrm{s})}+5C{\mathrm{a}}_{(\mathrm{s})}\stackrel{\mathrm{\Delta }}{\to }2{\mathrm{V}}_{(\mathrm{s})}+5Ca{\mathrm{O}}_{(\mathrm{s})}& \text{(III)}& \text{Decomposition reaction}\\ \text{(D)}& 2{\mathrm{H}}_2{\mathrm{O}}_{2(\mathrm{aq})}\stackrel{\mathrm{\Delta }}{\to }2{\mathrm{H}}_2{\mathrm{O}}_{(\mathrm{l})}+{\mathrm{O}}_{2(\mathrm{g})}& \text{(IV)}& \text{Displacement reaction}\end{array}$$ Choose the correct answer from the options given below:

1. A.A-III, B-IV, C-I, D-II
2. B.A-IV, B-I, C-II, D-III
3. C.A-II, B-III, C-I, D-IV
4. D.A-II, B-III, C-IV, D-I

Which of the following ions is the strongest oxidizing agent? (Atomic Number of $\mathrm{Ce}=58,\mathrm{Eu}=63,\mathrm{Tb}=65,\mathrm{Lu}=71$)

1. A.$\mathrm{L}{\mathrm{u}}^{3+}$
2. B.$\mathrm{E}{\mathrm{u}}^{2+}$
3. C.$\mathrm{T}{\mathrm{b}}^{4+}$
4. D.$\mathrm{C}{\mathrm{e}}^{3+}$

Based on the data given below : ${\mathrm{E}}_{\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}/C{\mathrm{r}}^{3+}}^{\circ }=1.33\text{ V}{\mathrm{E}}_{\mathrm{C}{\mathrm{l}}_2/C{\mathrm{l}}^{(-)}}^{\circ }=1.36\text{ V}$ ${\mathrm{E}}_{\mathrm{Mn}{\mathrm{O}}_4^{-}/M{\mathrm{n}}^{2+}}^0=1.51\text{ V}{\mathrm{E}}_{\mathrm{C}{\mathrm{r}}^{3+}/Cr}^{\circ }=-0.74\text{ V}$ the strongest reducing agent is :

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

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: Assertion A: The stability order of +1 oxidation state of $\text{Ga},\text{In}$ and $\text{Tl}$ is $\text{Ga}<\text{In}<\text{Tl}$. Reason R: The inert pair effect stabilizes the lower oxidation state down the group. In the light of the above statements, choose the correct answer from the options given below:

1. A.A is true but R is false.
2. B.Both A and R are true but R is NOT the correct explanation of A.
3. C.A is false but R is true.
4. D.Both A and R are true and R is the correct explanation of A.

Among the following halogens ${\mathrm{F}}_2,\mathrm{C}{\mathrm{l}}_2,\mathrm{B}{\mathrm{r}}_2$ and ${\mathrm{I}}_2$ Which can undergo disproportionation reactions?

1. A.${\mathrm{F}}_2$ and $\mathrm{C}{\mathrm{l}}_2$
2. B.$\mathrm{C}{\mathrm{l}}_2,\mathrm{B}{\mathrm{r}}_2$ and ${\mathrm{I}}_2$
3. C.Only ${\mathrm{I}}_2$
4. D.${\mathrm{F}}_2,\mathrm{C}{\mathrm{l}}_2$ and $\mathrm{B}{\mathrm{r}}_2$

Given below are two statements : Statement (I) : Fusion of $\mathrm{Mn}{\mathrm{O}}_2$ with $\mathrm{KOH}$ and an oxidising agent gives dark green ${\mathrm{K}}_2\mathrm{Mn}{\mathrm{O}}_4$. Statement (II) : Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion. In the light of the above statements, choose the correct answer from the options given below :

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

The number of ions from the following that are expected to behave as oxidising agent is : ${\text{Sn}}^{4+},{\text{Sn}}^{2+},{\text{Pb}}^{2+},{\text{Tl}}^{3+},{\text{Pb}}^{4+},{\text{Tl}}^{+}$

1. A.3
2. B.4
3. C.2
4. D.1

Match List I with List II. | LIST I (Reaction) | LIST II (Type of redox reaction) | | :--- | :--- | | A. ${\text{N}}_{2(g)}+{\text{O}}_{2(g)}\to 2{\text{NO}}_{(g)}$ | I. Decomposition | | B. $2\text{Pb}({\text{NO}}_3{)}_{2(s)}\to 2{\text{PbO}}_{(s)}+4{\text{NO}}_{2(g)}+{\text{O}}_{2(g)}$ | II. Displacement | | C. $2{\text{Na}}_{(s)}+2{\text{H}}_2{\text{O}}_{(l)}\to 2{\text{NaOH}}_{(aq.)}+{\text{H}}_{2(g)}$ | III. Disproportionation | | D. $2{\text{NO}}_{2(g)}+2{\text{OH}}_{(aq.)}^{-}\to {\text{NO}}_{2(aq.)}^{-}+{\text{NO}}_{3(aq.)}^{-}+{\text{H}}_2{\text{O}}_{(l)}$ | IV. Combination | Choose the correct answer from the options given below :

1. A.(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
2. B.(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
3. C.(A)-(II), (B)-(III), (C)-(IV), (D)-(I)
4. D.(A)-(III), (B)-(II), (C)-(I), (D)-(IV)

The element which shows only one oxidation state other than its elemental form is :

1. A.Nickel
2. B.Titanium
3. C.Cobalt
4. D.Scandium

Which of the following reactions are disproportionation reactions? (A) $\mathrm{C}{\mathrm{u}}^{+}\to \mathrm{C}{\mathrm{u}}^{2+}+\mathrm{Cu}$ (B) $3Mn{\mathrm{O}}_4^{2-}+4{\mathrm{H}}^{+}⟶2Mn{\mathrm{O}}_4^{-}+\mathrm{Mn}{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$ (C) $2KMn{\mathrm{O}}_4⟶{\mathrm{K}}_2\mathrm{Mn}{\mathrm{O}}_4+\mathrm{Mn}{\mathrm{O}}_2+{\mathrm{O}}_2$ (D) $2Mn{\mathrm{O}}_4^{-}+3M{\mathrm{n}}^{2+}+2{\mathrm{H}}_2\mathrm{O}⟶5Mn{\mathrm{O}}_2+4{\mathrm{H}}^{+}$ Choose the correct answer from the options given below :

1. A.(A), (B)
2. B.(A), (D)
3. C.(B), (C), (D)
4. D.(A), (B), (C)

The lowest oxidation number of an atom in a compound ${\mathrm{A}}_2\mathrm{B}$ is $-2$. The number of electrons in its valence shell is ________ .

Given below are two statements : Statement (I) : Dimethyl glyoxime forms a six-membered covalent chelate when treated with $\mathrm{NiC}{\mathrm{l}}_2$ solution in presence of $\mathrm{N}{\mathrm{H}}_4\mathrm{OH}$. Statement (II) : Prussian blue precipitate contains iron both in $(+2)$ and $(+3)$ oxidation states. In the light of the above statements, choose the most appropriate answer from the options given below :

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

The strongest reducing agent among the following is :

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