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d- and f-Block Elements · Question 31

JEE Main 2025 (Online) 4th April Evening ShiftMCQMedium📈 Topic in 13% papers+4−1
1

The incorrect relationship in the following pairs in relation to ionisation enthalpies is :

  1. Mn2+ < Fe2+
  2. Mn+ < Mn2+
  3. Mn+ < Cr+
  4. Fe2+ < Fe3+

Answer

(1) Mn2+ < Fe2+

Solution

Ionisation enthalpy of an ion = energy needed to remove one more electron from it.

(1) Mn2+ (3d5, stable half-filled) Mn3+: i H3(Mn) = 3248 kJ mol-1

Fe2+ (3d6) Fe3+ (3d5): i H3(Fe) = 2957 kJ mol-1

Mn2+ > Fe2+; so ' Mn2+ < Fe2+' is incorrect.

(2) Mn+ (1509) < Mn2+ (3248): an electron is removed more easily from the less charged ion. Correct.

(3) Mn+ (3d5 4s1, loses 4s electron, 1509) < Cr+ (3d5, stable, 1592). Correct.

(4) Fe2+ (2957) < Fe3+ (higher charge and stable 3d5, about 5290). Correct.

Answer: (1)

JEE Main 2025 (Online) 4th April Evening Shift

Keep practising — d- and f-Block Elements

2

The metal ions that have the calculated spin-only magnetic moment value of 4.9 B.M. are : Choose the correct answer from the options given below:

  1. A, D and E Only
  2. A, B and E Only
  3. A, C and E Only
  4. B and E Only
JEE Main 2025 (Online) 3rd April Morning Shift
3

Consider the following reactions A + Little amountNaCl + H2SO4 CrO2Cl2 + Side Products CrO2Cl2(Vapour) + NaOH B + NaCl + H2O B + H+ C + H2O The number of terminal 'O' present in the compound 'C' is

JEE Main 2025 (Online) 3rd April Morning Shift
4

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 2025 (Online) 3rd April Evening Shift
5

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).

JEE Main 2025 (Online) 3rd April Evening Shift
6

The spin-only magnetic moment value of Mn+ ion formed among Ni, Zn, Mn and Cu that has the least enthalpy of atomisation is . (in nearest integer) Here n is equal to the number of diamagnetic complexes among K2[NiCl4], [Zn(H2O)6]Cl2, K3[Mn(CN)6] and [Cu(PPh3)3I]

JEE Main 2025 (Online) 2nd April Evening Shift
7

The correct option with order of melting points of the pairs (Mn, Fe), (Tc, Ru) and (Re, Os) is :

  1. Fe < Mn, Ru < Tc and Re < Os
  2. Fe < Mn, Ru < Tc and Os < Re
  3. Mn < Fe, Tc < Ru and Re < Os
  4. Mn < Fe, Tc < Ru and Os < Re
JEE Main 2025 (Online) 29th January Morning Shift
8

The molar mass of the water insoluble product formed from the fusion of chromite ore (FeCr2O4) with Na2CO3 in presence of O2 is g mol-1.

JEE Main 2025 (Online) 29th January Morning Shift
9

Consider 'n' is the number of lone pair of electrons present in the equatorial position of the most stable structure of ClF3. The ions from the following with 'n' number of unpaired electrons are Choose the correct answer from the options given below:

  1. B and D Only
  2. A, D and E Only
  3. B and C Only
  4. A and C Only
JEE Main 2025 (Online) 28th January Morning Shift
10

Which of the following oxidation reactions are carried out by both K2Cr2O7 and KMnO4 in acidic medium? Choose the correct answer from the options given below :

  1. A, B and C Only
  2. C, D and E Only
  3. B, C and D Only
  4. A, D and E Only
JEE Main 2025 (Online) 28th January Morning Shift
11

The amphoteric oxide among V2O3, V2O4 and V2O5, upon reaction with alkali leads to formation of an oxide anion. The oxidation state of V in the oxide anion is :

  1. + 4
  2. + 5
  3. + 3
  4. + 7
JEE Main 2025 (Online) 28th January Evening Shift

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