Which of the following species has a regular tetrahedral structure?

The outer orbitals of $C$ in ethene molecule can be considered to be hybridized to give three equivalent $sp^2$ orbitals. The total number of sigma $(\sigma)$ and pi $(\pi)$ bonds in ethene molecule is

Among the following transformations,the hybridisation of the central atom remains unchanged in

In $PCl_5$, phosphorus is in $sp^3d$ hybridised state but all its five bonds are not equivalent. Justify your answer with reason.

Which of the following molecular geometries is not produced by $sp^3$ hybridisation?

What is the type of hybridization of the central atom in the following molecules: $BeCl_2, CO_2, BH_3, BCl_3$?