s and p Overlap

Q. The Be-Cl bonds in $BeC{l}_2$ are formed due to overlap of ____ and ____ orbitals.

1. p , p
2. s , p
3. sp , p
4. sp , s

Q. Give the structural formula for the following :​

(iv) Acetone​

Q. Why is angle between two bonds in tetrahedral model 109°28?