How many lone pairs of electrons are present in a hydroxyl ion?

Observe the following species:
$(i)$ $NH_3$
$(ii)$ $AlCl_3$
$(iii)$ $SnCl_4$
$(iv)$ $CO_2$
$(v)$ $Ag^{+}$
$(vi)$ $HSO_4^{-}$
How many of the above species act as Lewis acids?

The decreasing order of bond angles in $BF_3$,$NH_3$,$PF_3$ and $I_3^-$ is

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.

$A$ lone pair of electrons in an atom implies

Assertion : The $S-S-S$ bond angle in $S_8$ molecule is $105^o$.
Reason : $S_8$ has a $V$-shape.