Question

who is john Dalton ...and what was his theory

Answer 1

Heya,

John Dalton was an English chemist, physicist, and meteorologist. 

He proposed that all matter was composed of atoms which are indivisible building blocks

HOPE IT HELPS:-))

Answer 2

Here's your answer.
Actually I had a book containing this, and I took a snap from the section.

Hope it'll help. :-)