In some of the reactions thallium resembles aluminium, whereas in others it resembles with group $1$ metals. Support this statement by giving some evidences.

Boron form covalent compound due to

Three pairs of compounds are given below. Identify that compound in each of the pairs which has group $-13$ element in more stable oxidation state. Give reason for your choice. State the nature of bonding also. $(A)$ $TlCl_3, TlCl$ $(B)$ $AlCl, AlCl$ $(C)$ $InCl_3, InCl$

Explain structures of diborane and boric acid.

Draw structure of $Al_2Cl_6$ and give uses of $AlCl_3$.