How many atomic orbitals of each type mix to form hybrid orbitals of the central atom in cl2o?

In here Oxygen is the central atom. It makes two bonds with Cl and has two lone pairs. Since, the shape is bent and the hybridization is sp3. Molecular geometry is a bit dissimilar from hybridization. Hybridization is reliant on the number of bonds and lone pairs. Since O has two bonds with Cl, its hybridization is sp3. It is like is this: 1 lone pair/bond = s. 2 lone pairs/bond = sp 3 lone pairs/bonds = sp2, etc. molecular geometry, you count the number of bonds and lone pairs. This has two bonds and 2 lone pairs so if they were all bonds, the molecule would be tetrahedral. 

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.