In the reaction $AlCl_3 + Cl^- \rightarrow [AlCl_4]^-$,$AlCl_3$ acts as a.......

Which of the following compounds does not exist?

The number of sigma $(\sigma)$ and pi $(\pi)$ bonds in peroxodisulphuric acid are, respectively:

Fill in the blanks given below:
$(i)$ The two theories based on the principles of quantum mechanics are ........ and ......... .
$(ii)$ The electronic configuration of carbon in the excited state is ........... .
$(iii)$ Through the combination of atomic orbitals,....... are formed.
$(iv)$ The ${\rm{CH}}_4$ molecule has a .......... shape.

Which of the following is incorrectly matched?

Identify the correct option.