Assertion: ${\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_{6}\right]}^{3-}$ ion shows magnetic moment corresponding to two unpaired electrons.

Reason: Because it has ${d}^{2}s{p}^{3}$ type hybridization.

1.  Both assertion and reason are true and the reason is the correct explanation of assertion.

2.  Both assertion and reason are true and the reason is not the correct explanation of assertion.

3.  Assertion is true but the reason is false.

4.  Assertion is false but the reason is true.

Hint: CN is a strong field ligand

According to VBT, the orbital diagram of Fe3+ in ${\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_{6}\right]}^{3-}$ is

Hybridization = ${d}^{2}s{p}^{3}$

n=1

Hence, the correct assertion is

Hence, the Assertion is false but the reason is true.