Question

Going microscopically using the Newton’s 3rd law of motion, can you justify the
existence of up thrust or buoyant force?

Answer 1

Most of the time when we go for Microscopic level physics means towards Quantum World and Quantum mechanics, Newton's Laws Fail.

but, here we can atleast visualise it.

Buoyant Force or Upthrust is a component of Normal Force resultant of another Normal Force which are action reaction pair of N III LM