The shape of methane molecule is

The number of species from the following in which the central atom uses $sp^3$ hybrid orbitals in its bonding is . . . . . . .
$NH_3, SO_2, SiO_2, BeCl_2, CO_2, H_2O, CH_4, BF_3$

What is meant by hybridisation of atomic orbitals? Describe the shapes of $sp$,$sp^{2}$,$sp^{3}$ hybrid orbitals.

Methane is tetrahedral but not square planar in nature,prove it.

The species in which the $N$ atom is in a state of $sp$ hybridization is:

Which set of hybridisation is correct for the following compounds:
$NO_2$,$SF_4$,$PF_6^-$