Question

why are drops and bubbles are spherical

Answer 1

Bubbles are round — spherical — because there is an attractive force called surface tension that pulls molecules of water into the tightest possible groupings. And the tightest possible grouping that any collection of particles can achieve is to pack together into a sphere.

Answer 2

The cohesive forces between liquidmolecules is responsible for the surface tension. The molecules of water on the surface don't have like molecules around it. ... So the water droplets tend to be pulled into shape of spherical due to cohesive forces.