What is the hybridization of the beryllium atom in beryllium fluoride $(BeF_2)$?

In which of the following combinations does the hybridisation of the central atom $(^*)$ $NOT$ change?

Hybridisation state of $C$ in diamond is

$KI + MnO_2 + H_2SO_4 \to$ Vapours $(B) +$ other products
Vapours $(B) + K_2S_2O_8 \to (C) + (D)$
$(D) \xrightarrow{(B)}$ Brown $(E)$
Hybridisation of central atom in $(E)$ is

How many $sp^{2}$ and $sp-$ hybridised carbon atoms are present respectively in the following compound?

Which is the correct statement?
As the $s$-character of a hybrid orbital decreases:
$(I)$ The bond angle decreases
$(II)$ The bond strength increases
$(III)$ The bond length increases
$(IV)$ Size of orbitals increases