In the complex ion $[Cr(H_2O)_6]^{3+}$,the coordination number of $Cr$ is:

Identify the neutral complex from the following.

Which of the following complexes is neutral?

Given the molecular formulas of the hexa-coordinated complexes: $(a)$ $CoCl_3 \cdot 6NH_3$,$(b)$ $CoCl_3 \cdot 5NH_3$,$(c)$ $CoCl_3 \cdot 4NH_3$. If the number of coordinated $NH_3$ molecules in $(a)$,$(b)$,and $(c)$ are $6, 5$,and $4$ respectively,the primary valencies in $(a)$,$(b)$,and $(c)$ are:

The molecular formula of potash alum is

The coordination number of a central metal atom in a complex is determined by: