d- and f-Block Elements · JEE Main previous year questions

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2025 9 questions

Q642025 · 8 Apr 2025 · Shift 2
The correct decreasing order of spin only magnetic moment values (BM) of $C u^{+}$ , $C u^{2 +}$ , $C r^{2 +}$ and $C r^{3 +}$ ions is :
1. A. $C r^{3 +} > C r^{2 +} > C u^{+} > C u^{2 +}$
2. B. $C u^{+} > C u^{2 +} > C r^{3 +} > C r^{2 +}$
3. C. $C r^{2 +} > C r^{3 +} > C u^{2 +} > C u^{+}$
4. D. $C u^{2 +} > C u^{+} > C r^{2 +} > C r^{3 +}$
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Answer: C
Q552025 · 4 Apr 2025 · Shift 1
Pair of transition metal ions having the same number of unpaired electrons is
1. A. $T i^{3 +}, M n^{2 +}$
2. B. $T i^{2 +}, C o^{2 +}$
3. C. $F e^{3 +}, C r^{2 +}$
4. D. $V^{2 +}, C o^{2 +}$
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Answer: D
Q732025 · 4 Apr 2025 · Shift 1· Numerical answer
Fortification of food with iron is done using $FeS O_{4} \cdot 7 H_{2} O$ . The mass in grams of the $FeS O_{4} \cdot 7 H_{2} O$ required to achieve 12 ppm of iron in 150 kg of wheat is ____ (Nearest integer) [Given: Molar mass of Fe, S and O respectively are 56, 32 and $16 g mo l^{- 1}$ ]
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Answer: 9
Q652025 · 3 Apr 2025 · Shift 1
The metal ions that have the calculated spin-only magnetic moment value of 4.9 B.M. are : A. $C r^{2 +}$ B. $F e^{2 +}$ C. $F e^{3 +}$ D. $C o^{2 +}$ E. $M n^{3 +}$ Choose the correct answer from the options given below:
1. A.A, D and E Only
2. B.A, B and E Only
3. C.A, C and E Only
4. D.B and E Only
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Answer: B
Q732025 · 3 Apr 2025 · Shift 2· Numerical answer
Among, $Sc, Mn, Co$ and $Cu$ , identify the element with highest enthalpy of atomisation. The spin only magnetic moment value of that element in its $+ 2$ oxidation state is__________ $BM$ (in nearest integer).
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Answer: 4
Q612025 · 29 Jan 2025 · Shift 2
The calculated spin-only magnetic moments of $K_{3} [Fe (OH)_{6}]$ and $K_{4} [Fe (OH)_{6}]$ respectively are :
1. A. $4.90$ and $4.90 B.M.$
2. B. $4.90$ and $5.92 B.M.$
3. C. $5.92$ and $4.90 B.M.$
4. D. $3.87$ and $4.90 B.M.$
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Answer: C
Q682025 · 28 Jan 2025 · Shift 1
Which of the following oxidation reactions are carried out by both $K_{2} C r_{2} O_{7}$ and $KMn O_{4}$ in acidic medium? A. $I^{-} \to I_{2}$ B. $S^{2 -} \to S$ C. $F e^{2 +} \to F e^{3 +}$ D. $I^{-} \to I O_{3}^{-}$ E. $S_{2} O_{3}^{2 -} \to S O_{4}^{2 -}$ Choose the correct answer from the options given below :
1. A.A, B and C Only
2. B.C, D and E Only
3. C.B, C and D Only
4. D.A, D and E Only
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Answer: A
Q522025 · 24 Jan 2025 · Shift 2
Match List - I with List - II. | List - I (Transition metal ion) | List - II (Spin only magnetic moment (B.M.)) | | :--- | :--- | | (A) $Ti^{3 +}$ | (I) 3.87 | | (B) $V^{2 +}$ | (II) 0.00 | | (C) $Ni^{2 +}$ | (III) 1.73 | | (D) $Sc^{3 +}$ | (IV) 2.84 | Choose the correct answer from the options given below :
1. A.(A) – (III), (B) – (I), (C) – (IV), (D) – (II)
2. B.(A) – (II), (B) – (IV), (C) – (I), (D) – (III)
3. C.(A) – (III), (B) – (I), (C) – (II), (D) – (IV)
4. D.(A) – (IV), (B) – (II), (C) – (III), (D) – (I)
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Answer: A
Q612025 · 22 Jan 2025 · Shift 1
Lanthanoid ions with $4 f^{7}$ configuration are : (A) $Eu^{2 +}$ (B) $Gd^{3 +}$ (C) $Eu^{3 +}$ (D) $Tb^{3 +}$ (E) $Sm^{2 +}$ Choose the correct answer from the options given below :
1. A.(B) and (E) only
2. B.(B) and (C) only
3. C.(A) and (D) only
4. D.(A) and (B) only
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Answer: D