Question

Match List-I with List-II

Choose the correct answer from the options given below :

• A. (A)-(III), (B)-(I), (C)-(II), (D)-(IV)
• B. (A)-(I), (B)-(IV), (C)-(II), (D)-(III)
• C. (A)-(I), (B)-(III), (C)-(II), (D)-(IV)
• D. (A)-(II), (B)-(III), (C)-(IV), (D)-(I)

Hint:

Remember that primary valency is the oxidation state and secondary valency is the coordination number. For polydentate ligands, multiply the denticity by the number of ligands to calculate their contribution to the secondary valency.

Answer 1

The Correct Option is B

To correctly match List-I with List-II, we need to determine the primary and secondary valencies for each of the complex compounds given in List-I. Primary valency refers to the oxidation state of the central metal atom, while secondary valency corresponds to the coordination number, which is the number of ligand atoms bonded to the central metal atom. 

1. (A) \([Co(en)_2Cl_2]Cl\):
   • Primary Valency: Co is in the oxidation state +3.
   • Secondary Valency: En (ethylenediamine) is a bidentate ligand, and there are two such ligands contributing four coordination sites. Additionally, there are two chlorides bonded to cobalt, making the coordination number 6.
2. (B) \([Pt(NH_3)_2Cl(NO_2)]\):
   • Primary Valency: Pt is in the oxidation state +4.
   • Secondary Valency: The coordination number is 4 (NH₃, Cl, and NO₂).
3. (C) \(Hg[Co(SCN)_4]\):
   • Primary Valency: Hg is in the oxidation state +2.
   • Secondary Valency: There are four SCN ligands, making the coordination number 4.
4. (D) \([Mg(EDTA)]^{2-}\):
   • Primary Valency: Mg is in the oxidation state +2.
   • Secondary Valency: EDTA is a hexadentate ligand, contributing six coordination sites; however, here it uses four, making the coordination number 4.

Based on this analysis, the correct matching is:

• (A) - (I): Primary Valency 3, Secondary Valency 6
• (B) - (IV): Primary Valency 4, Secondary Valency 4
• (C) - (II): Primary Valency 2, Secondary Valency 4
• (D) - (III): Primary Valency 2, Secondary Valency 4

Thus, the correct answer is: (A)-(I), (B)-(IV), (C)-(II), (D)-(III).

Answer 2

Step 1: Understand Primary and Secondary Valency.
Primary Valency: Corresponds to the oxidation state of the central metal ion. It is satisfied by negative ions.
Secondary Valency: Corresponds to the coordination number of the central metal ion, i.e., the number of ligands directly bonded to it. It is satisfied by neutral molecules or negative ions and determines the geometry of the complex.
Step 2: Determine Primary and Secondary Valency for each complex in List-I.
(A) \( [Co(en)_2Cl_2]Cl \) Primary Valency (Oxidation State of Co): +3
Secondary Valency (Coordination Number of Co): 6
(A) - (I) (B) \( [Pt(NH_3)_2Cl(NO_2)] \) Primary Valency (Oxidation State of Pt): +2
Secondary Valency (Coordination Number of Pt): 4
(B) - (IV)
(C) \( Hg[Co(SCN)_4] \) Primary Valency (Oxidation State of Co): +2 Secondary Valency (Coordination Number of Co): 4
(C) - (II) (D) \( [Mg(EDTA)]^{2-} \)
Primary Valency (Oxidation State of Mg): +2
Secondary Valency (Coordination Number of Mg): 6
(D) - (III)
Step 3: Match the pairs.
(A) - (I)
(B) - (IV)
(C) - (II)
(D) - (III)
Step 4: Choose the correct option.
The correct matching is given by option (2).