Question

Assertion: Charge on the complex of a ferric ion with EDTA is minus one.

Reason: EDTA is a hexadentate ligand.

• A. Both Assertion and Reason are True
• B. Assertion is True and Reason is False
• C. Assertion is False and Reason is False
• D. Assertion is True and Reason is NOT a correct explanation for Assertion.

Answer 1

The correct option is D

Assertion is True and Reason is NOT a correct explanation for Assertion.

Explanation for assertion:-

• EDTA is Ethylenediaminetetraacetic acid with a chemical formula of $[{\mathrm{CH}}_2\mathrm{N}{\left({\mathrm{CH}}_2{\mathrm{CO}}_2\mathrm{H}\right)}_2{]}_2$.
• This EDTA has charge of -4, on the other hand, Iron has a charge of +3
• $\therefore$The net charge on the complex becomes: $-4+3=-1$
• Thus assertion is true.

Explanation for reason:-

• ${\mathrm{EDTA}}^{4-}$ (ethylene diamine tetracetate ion) is a hexadentate ligand that can bind to the central metal ion by two nitrogen and four oxygen atoms.
• For most of the transition metals this ${\mathrm{EDTA}}^{4-}$ forms very stable complexes.
• With most of the transition metals, this hexadentate ligand forms very stable complexes and they are usually octahedral structures.
• The two Nitrogen atoms and the four Oxygen atoms which are negatively charged are the donor atoms in ${\mathrm{EDTA}}^{4-}$.
• Thus the reason is also true but it is not the correct explanation for the assertion.

Therefore, option (D) Assertion is True and Reason is NOT a correct explanation for Assertion, is the correct answer.