Q1. To calculate the spin-only magnetic moment, you only need to know the number of unpaired electrons in the complex. In the case of V2+ ion, it is 3 (it is a d3 system).
Next we must know the type of ligand field, which is octahedral is 6 water molecules are coordinating to the V2+ ion. The three unpaired electrons will be in the d-orbitals in the lower energy t2g set, one electron in each orbital.
The spin-only magnetic moment, μs.o. , is,
μs.o. = √[4S(S+1)]
S is the sum of the spin quantum numbers of the unpaired electrons. If there are n unpaired electrons, then the sum will be n(½) = n/2. Putting n/2 in place of S in the equation gives,
μs.o. = √[n(n + 2)]
which is a simpler equation. The values of μs.o. from this equation are,
n μs.o.
0 0
1 1.73
2 2.83
3 3.87
4 4.90
5 5.92
Q2.
The two unpaired electrons are in the higher energy eg set of d-orbitals.
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Q4. Four ammine ligands plus two chloro ligands, all monodentate, makes the coordination number 6 (octahedral). The other chloride ion is outside of the coordination sphere (not in the brackets [ ] ).
Q5. Look again! 