Question

Atomic number of Cr and Fe are respectively 24 and 26. which of the following is paramagnetic with the spin of electron ?

(a) [Cr(Co)₆]

(b) [Fe(CO)₅]

(c) [Fe(CN)₆]^4-

(d) [Cr(NH₃)₆]³⁺

Answer 1

Correct option (d) [Cr(NH₃)₆]³⁺

Explanation :

Odd electrons, ions and molecules are paramagnetic.

In Cr(CO)₆ molecule 12 electrons are contributed by CO group and it contains no odd electron.

Fe(CO)₅ molecule also does not contain odd electron.

This ion contains odd electron so it is paramagnetic.