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d- and f-Block Elements · Question 18

JEE Main 2026 (Online) 24th January Evening ShiftMCQEasy📈 Topic in 16% papers+4−1
1

"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

Answer

(4) green

Solution

Lightest element of group 7 = Mn (Z = 25).

Oxoanion of Mn in the +6 state = manganate ion, MnO42- (X).

Potassium salt = potassium manganate, K2MnO4.

As per NCERT: 2MnO2 + 4KOH + O2 2K2MnO4 + 2H2O, and K2MnO4 is dark green.

(KMnO4, Mn +7, is purple.)

Answer: (4)

JEE Main 2026 (Online) 24th January Evening Shift

Keep practising — d- and f-Block Elements

2

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
3

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
4

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
5

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
6

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
7

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
8

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
9

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
10

The number of valence electrons present in the metal among Cr, Co, Fe and Ni which has the lowest enthalpy of atomisation is :

  1. 10
  2. 6
  3. 9
  4. 8
JEE Main 2025 (Online) 7th April Morning Shift
11

'X' is the number of acidic oxides among VO2, V2O3, CrO3, V2O5 and Mn2O7. The primary valency of cobalt in [Co(H2NCH2CH2NH2)3]2(SO4)3 is Y. The value of X + Y is .

  1. 3
  2. 4
  3. 2
  4. 5
JEE Main 2025 (Online) 7th April Evening Shift

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