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Coordination Compounds · Question 17

JEE Main 2026 (Online) 28th January Evening ShiftNumericalMedium📈 Topic in 55% papers+4
1

The number of isoelectronic species among Sc3+, Cr2+, Mn3+, Co3+ and Fe3+ is ‘n’. If ‘n’ moles of AgCl is formed during the reaction of complex with formula CoCl3(en)2NH3 with excess of AgNO3 solution, then the number of electrons present in the t2g orbital of the complex is .

Answer

6

Solution

Number of electrons:

Sc3+ = 21 - 3 = 18, Cr2+ = 24 - 2 = 22, Mn3+ = 25 - 3 = 22, Co3+ = 27 - 3 = 24, Fe3+ = 26 - 3 = 23

only Cr2+ and Mn3+ are isoelectronic n = 2

1 mol of the complex gives 2 mol AgCl two Cl- are outside the coordination sphere.

Coordination number 6 = 2 en (bidentate, 4) + NH3 (1) + Cl (1)

complex is [Co(en)2(NH3)Cl]Cl2

Co3+: [Ar] 3d6; en and NH3 are strong field ligands low spin t2g6 eg0

electrons in t2g orbitals = 6

Answer: 6

JEE Main 2026 (Online) 28th January Evening Shift

Keep practising — Coordination Compounds

2

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

  1. Both Statement I and Statement II are false
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are true
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 24th January Morning 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 false
  3. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are true
JEE Main 2026 (Online) 24th January Morning Shift
4

Consider a mixture 'X' which is made by dissolving 0.4 mol of [Co(NH3)5SO4]Br and 0.4 mol of [Co(NH3)5Br]SO4 in water to make 4 L of solution. When 2 L of mixture 'X' is allowed to react with excess of AgNO3, it forms precipitate 'Y'. The rest 2 L of mixture 'X' reacts with excess BaCl2 to form precipitate 'Z'. Which of the following statements is CORRECT?

  1. 0.1 mol of 'Y' is formed.
  2. 0.4 mol of 'Z' is formed.
  3. 0.2 mol of 'Z' is formed.
  4. 'Y' is BaSO4 and 'Z' is AgBr.
JEE Main 2026 (Online) 24th January Morning Shift
5

The wavelengths of light absorbed for the following complexes are in the order (I) [Co(NH3)6]3+ ; (II) [Co(H2O)6]3+ ; (III) [Co(CN)6]3- ; (IV) [Co(NH3)5(H2O)]3+ ; (V) [CoF6]3-

  1. III < IV < I < II < V
  2. III < I < IV < V < II
  3. III < I < IV < II < V
  4. III < I < II < IV < V
JEE Main 2026 (Online) 24th January Evening Shift
6

A chromium complex with a formula CrCl3 6H2O has a spin only magnetic moment value of 3.87 BM and its solution conductivity corresponds to 1 : 2 electrolyte. 2.75 g of the complex solution was initially passed through a cation exchanger. The solution obtained after the process was reacted with excess of AgNO3. The amount of AgCl formed in the above process is g. (Nearest integer) [Given: Molar mass in g mol-1 Cr : 52, Cl : 35.5, Ag : 108, O : 16, H : 1]

JEE Main 2026 (Online) 24th January Evening Shift
7

The statements that are incorrect about the nickel(II) complex of dimethylglyoxime are : Choose the correct answer from the options given below :

  1. C and E Only
  2. A, D and B Only
  3. B, C and E Only
  4. C and D Only
JEE Main 2026 (Online) 23rd January Morning Shift
8

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

  1. Both Statement I and Statement II are false
  2. Both Statement I and Statement II are true
  3. Statement I is false but Statement II is true
  4. Statement I is true but Statement II is false
JEE Main 2026 (Online) 23rd January Morning Shift
9

The crystal field stabilisation energy of [Co(oxalate)3]3- complex is 'n' times that of the [Cr(oxalate)3]3- complex. Here 'n' is . (Assume o P)

JEE Main 2026 (Online) 23rd January Morning Shift
10

Identify the CORRECT set of details from the following : Choose the correct answer from the options given below :

  1. C & D Only
  2. A, C & E Only
  3. A, B, C, D & E
  4. A, B & D Only
JEE Main 2026 (Online) 23rd January Evening Shift
11

Total number of unpaired electrons present in the central metal atoms/ions of [Ni(CO)4], [NiCl4]2-, [PtCl2(NH3)2], [Ni(CN)4]2- and [Pt(CN)4]2- is .

JEE Main 2026 (Online) 23rd January Evening Shift

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