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d- and f-Block Elements · Question 16

JEE Main 2026 (Online) 28th January Morning ShiftMCQMedium📈 Topic in 32% papers+4−1
1

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

  1. Statement I is false but Statement II is true
  2. Both Statement I and Statement II are false
  3. Both Statement I and Statement II are true
  4. Statement I is true but Statement II is false

Answer

(2) Both Statement I and Statement II are false

Solution

Statement I: a transition metal ion is coloured when it has partly filled d orbitals (d1 to d9), allowing d–d transitions.

Sc3+ (3d0) colourless, Ti3+ (3d1) coloured pair not counted

Mn2+ (3d5) coloured, Cr2+ (3d4) coloured pair counted

Cu2+ (3d9) coloured, Zn2+ ( 3d10) colourless pair not counted

Ni2+ (3d8) coloured, Ti4+ (3d0) colourless pair not counted

Only 1 pair has both ions coloured, not 3. Statement I is false.

Statement II: Th4+ (5f0, noble gas core), Ce4+ (4f0) and Gd3+ (4f7) are stable states with no tendency to lose electrons; Ce4+ is in fact a strong oxidant.

Eu2+ (4f7) readily changes to the common +3 state ( Eu2+ Eu3+ + e-), so as per NCERT it is a strong reducing agent.

Eu2+, not Th4+, is the strongest reducing agent. Statement II is false.

Answer: (2)

JEE Main 2026 (Online) 28th January Morning Shift

Keep practising — d- and f-Block Elements

2

Consider the following statements about manganate and permanganate ions. Identify the correct statements. Choose the correct answer from the options given below :

  1. A and D Only
  2. A, B and C Only
  3. A, C and D Only
  4. A, D and E Only
JEE Main 2026 (Online) 28th January Evening Shift
3

"X" is an oxoanion of the lightest element of group 7 (in the periodic table). The metal is in +6 oxidation state in "X". The color of the potassium salt of X is

  1. purple
  2. orange
  3. yellow
  4. green
JEE Main 2026 (Online) 24th January Evening Shift
4

The oxidation state of chromium in the final product formed in the reaction between KI and acidified K2Cr2O7 solution is :

  1. +2
  2. +3
  3. +4
  4. +6
JEE Main 2026 (Online) 23rd January Evening Shift
5

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Statement I is true but Statement II is false
  2. Both Statement I and Statement II are true
  3. Both Statement I and Statement II are false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 22nd January Evening Shift
6

Among the following oxides of 3d elements, the number of mixed oxides are . Ti2O3, V2O4, Cr2O3, Mn3O4, Fe3O4, Fe2O3, Co3O4

JEE Main 2026 (Online) 22nd January Evening Shift
7

MnO42-, in acidic medium, disproportionates to :

  1. MnO4- and MnO
  2. MnO4- and MnO2
  3. Mn2O7 and MnO2
  4. Mn2O7 and MnO
JEE Main 2026 (Online) 21st January Morning Shift
8

Consider the following reactions : NaCl + K2Cr2O7 + H2SO4 A + KHSO4 + NaHSO4 + H2O A + NaOH B + NaCl + H2O B + H2SO4 + H2O2 C + Na2SO4 + H2O In the product 'C', 'X' is the number of O22- 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 .

JEE Main 2026 (Online) 21st January Morning Shift
9

Given below are some of the statements about Mn and Mn2O7. Identify the correct statements. Choose the correct answer from the options given below :

  1. A, B, C and D
  2. A, B and D Only
  3. A, B and C Only
  4. A, C and D Only
JEE Main 2026 (Online) 21st January Evening Shift
10

The correct decreasing order of spin only magnetic moment values (BM) of Cu+, Cu2+, Cr2+ and Cr3+ ions is :

  1. Cr3+ > Cr2+ > Cu+ > Cu2+
  2. Cu+ > Cu2+ > Cr3+ > Cr2+
  3. Cr2+ > Cr3+ > Cu2+ > Cu+
  4. Cu2+ > Cu+ > Cr2+ > Cr3+
JEE Main 2025 (Online) 8th April Evening Shift
11

The first transition series metal 'M' has the highest enthalpy of atomisation in its series. One of its aquated ions ( Mn+) exists in green colour. The nature of the oxide formed by the above Mn+ ion is:

  1. basic
  2. neutral
  3. amphoteric
  4. acidic
JEE Main 2025 (Online) 7th April Morning Shift

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