Question

how can we seprate good healthy seeds from damaged ones

Answer 1

if we dip the seeds in water then we will observe that some seeds will flow over water those seeds are hollow or damaged and rest of it are healthy.

Answer 2

We can easily do it by:
Take a bowl/ jug and add water into it . Then add the vegetable/ cereals into it. You will observe that some seed are floating on the top of water but some are not floating. The seeds which are floating on top of water are damaged seeds but which are not floating are good seeds. In this way you can seperate good seeds from damaged seeds.