Which of the following statements are correct? (A) The M 3 + / M 2 + reduction potential for iron is greater than manganese. (B) The higher oxidation states of first row d-block elements get stabilize

Question

Which of the following statements are correct?

(A) The $M^{3 +} / M^{2 +}$ reduction potential for iron is greater than manganese.

(B) The higher oxidation states of first row d-block elements get stabilized by oxide ion

(C) Aqueous solution of ${Cr}^{2 +}$ can liberate hydrogen from dilute acid

(D) Magnetic moment of $V^{2 +}$ is observed between $4.4 - 5.2 BM$

Choose the correct answer from the options given below:

TestHub · Accepted Answer

The valence electronic configuration of ${Mn}^{3 +}$ is $3 d^{4}$ and that of ${Mn}^{2 +}$ is stable $3 d^{5}$ .The valence electronic configuration of ${Fe}^{3 +}$ is $3 d^{5}$ and that of ${Fe}^{2 +}$ is $3 d^{6}$ .
The reduction electrode potential of ${Mn}^{3 +} / {Mn}^{2 +}$ is $+ 1.57 V$ while that of ${Fe}^{3 +} / {Fe}^{2 +}$ is $+ 0.77 V$ , hence A is wrong. Higher oxidation state of smaller $d$ -block elements is stabilised (or say form compounds) with smaller anion oxide that can be explained by stearic reason hence $B$ is correct.
The oxidation electrode potential of ${Cr}^{2 +} / {Cr}^{3 +}$ is $+ 0.41 V$ hence, it can reduce $H^{+}$ and so liberate $H_{2}$ .
The unpaired electrons in $V^{2 +}$ are $3$ hence, the magnetic moment of $V^{2 +}$ will be lesser than $4.4 BM$ .
Hence, only $B$ and $C$ are correct.

Chemistry - Complete d-block Question with Solution | TestHub

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