An onion peel was taken and

1.  placed in salt solution for five minutes.

2.  after that it was placed in distilled water.

When seen under the microscope what would be observed in (a) and (b)?

(a) Onion peel when placed in salt solution, shrinks as water from cells cytoplasm moves out of the cell £e., hypertonic solution.
(b) When it is placed again back in distilled water, Cell regains it's shape and absorbs water and become turgid (full of water) i.e., hypertonic solution.