The $ {[Fe(C{N_6})]^{3 - }} $ ion has magnetic moment of 1.73BM (Bohr Magnetic) while $ {[Fe{({H_2}O)_6}]^{3 + }} $ has a magnetic moment of 5.92BM. If true enter 1, else enter 0.

Hint: In this question first we need to find the hybridization of these two complexes and then with the help of hybridisation we will find the number of lone pair electrons. With the help of these lone pair electrons, we will be able to understand the magnetic moment of these two complexes.

Complete Step By Step Answer:
Hybridisation is a concept of mixing atomic orbitals into new hybrid orbitals which are generally of lower energy and suitable for the pairing of electrons to form chemical bonds in valence bond theory, or we can also define hybridization as the concept of mixing atomic orbitals to form new hybrid orbitals suitable for describing bonding properties. Hybridization helps to predict the shape and geometry of molecules and the way bonding happens in that.
Hybridization is important because it accommodates the shape of the molecule after promotion. When promotion occurs and the electrons are moved into higher energy orbitals, the resulting structure usually does not match the shape of the molecule. In order to make the resulting structure match the shape of the molecule, hybrid orbitals are created.
 $ {[Fe(C{N_6})]^{3 - }} $ has $ {d^3}s{p^3} $ hybridization which means that it has 1 lone pair of electrons.
 $ {[Fe{({H_2}O)_6}]^{3 + }} $ has $ s{p^3}{d^3} $ hybridisation which means that it has 5 lone pair of electrons.
Now, the formula to calculate the magnetic moment = $ \sqrt {N(N + 2)} BM $
Now, by putting the values of the lone pair of electrons in this formula, we find that $ {[Fe(C{N_6})]^{3 - }} $ has magnetic moment of 1.73 BM and $ {[Fe{({H_2}O)_6}]^{3 + }} $ has magnetic moment of 5.92 BM.
So, it is true that $ {[Fe(C{N_6})]^{3 - }} $ has magnetic moment of 1.73 BM and $ {[Fe{({H_2}O)_6}]^{3 + }} $ has magnetic moment of 5.92 BM.
Thus, the final answer is 1 (true).

Note:
Magnetic moment, also known as magnetic dipole moment, is the measure of the object's tendency to align with a magnetic field. Magnetic Moment is defined as magnetic strength and orientation of a magnet or other object that produces a magnetic field. The magnetic moment is a vector quantity.