$X$ is the number of electrons in $t_{2g}$ orbitals of the most stable complex ion among $[Fe(NH_3)_6]^{3+}$,$[Fe(Cl)_6]^{3-}$,$[Fe(C_2O_4)_3]^{3-}$ and $[Fe(H_2O)_6]^{3+}$. The nature of the oxide of vanadium of the type $V_2O_X$ is:

Ammonia is a Lewis base. It forms complexes with cations. Which one of the following cations does not form a complex with ammonia?

Given below are two statements:
Statement $I$ : $N(CH_3)_3$ and $P(CH_3)_3$ can act as ligands to form transition metal complexes.
Statement $II$: As $N$ and $P$ are from same group,the nature of bonding of $N(CH_3)_3$ and $P(CH_3)_3$ is always same with transition metals.
In the light of the above statements,choose the most appropriate answer from the options given below:

Identify the highest field strength ligand from the following.

The strongest ligand among the following is:

Urea reacts with water to form $A$ which will decompose to form $B$. $B$ when passed through $Cu^{2+}_{(aq)}$,a deep blue coloured solution $C$ is formed. What is the formula of $C$ from the following?