Redox Reactions · JEE Main previous year questions

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2026 8 questions

Q622026 · 4 Apr 2026 · Shift 2
Consider $∣ x ∣$ is the difference in oxidation states of $Mn$ in highest manganese fluoride and highest manganese oxide. The ions with $∣ x ∣$ number of unpaired electrons from the following are: A. $S c^{3 +}$ B. $Z n^{2 +}$ C. $V^{2 +}$ D. $F e^{2 +}$ E. $C o^{2 +}$ 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
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Answer: C
Q602026 · 2 Apr 2026 · Shift 1
Given below are two statements : Statement (I) : Oxidising power of halogens decreases in the order $F_{2} > C l_{2} > B r_{2} > I_{2}$ , which is the basis of "Layer test". Statement (II) : "Layer test" to identify $B r_{2}$ and $I_{2}$ in aqueous solution involves the oxidation of bromide or iodide into $B r_{2}$ or $I_{2}$ respectively with $C l_{2}$ , 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
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Answer: A
Q512026 · 28 Jan 2026 · Shift 1
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. $[S c^{3 +}, T i^{3 +}]$ , $[M n^{2 +}, C r^{2 +}]$ , $[C u^{2 +}, Z n^{2 +}]$ and $[N i^{2 +}, T i^{4 +}]$ Statement II : $T h^{4 +}$ is the strongest reducing agent among $T h^{4 +}$ , $C e^{4 +}$ , $G d^{3 +}$ and $E u^{2 +}$ . 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
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Answer: B
Q552026 · 28 Jan 2026 · Shift 2
Consider the following reactions $Na_{2} B_{4} O_{7} Δ 2 X + Y$ $CuSO_{4} + Y Non-Luminous flame Z + S O_{3}$ $2 Z + 2 X + Carbon Luminous flame 2 Q + Na_{2} B_{4} O_{7} + C O$ 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
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Answer: A
Q522026 · 23 Jan 2026 · Shift 2
The oxidation state of chromium in the final product formed in the reaction between KI and acidified $K_{2} Cr_{2} O_{7}$ solution is :
1. A.+2
2. B.+3
3. C.+4
4. D.+6
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Answer: B
Q732026 · 21 Jan 2026 · Shift 1· Numerical answer
Consider the following reactions : $NaCl + K_{2} C r_{2} O_{7} + H_{2} S O_{4} \to A + KHS O_{4} + NaHS O_{4} + H_{2} O$ $A + NaOH \to B + NaCl + H_{2} O$ $B + H_{2} S O_{4} + H_{2} O_{2} \to C + N a_{2} S O_{4} + H_{2} O$ In the product ' $C^{'}$ , ' $X$ ' is the number of $O_{2}^{2 -}$ units, ' $Y$ ' is the total number of oxygen atoms present and ' $Z$ ' is the oxidation state of $C r$ . The value of $X + Y + Z$ is ____.
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Answer: 13
Q522026 · 21 Jan 2026 · Shift 2
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. $C r O_{2} C l_{2}$ and +6
4. D. $C r O_{2} C l_{2}$ and +5
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Answer: C
Q552026 · 21 Jan 2026 · Shift 2
Given below are some of the statements about Mn and $M n_{2} O_{7}$ . Identify the correct statements. A. Mn forms the oxide $M n_{2} O_{7}$ , 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. $M n_{2} O_{7}$ is an ionic oxide. D. The structure of $M n_{2} O_{7}$ 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
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Answer: B