Question

defination of atom,molecule,law of constant proportion,law of chemical combination

Answer 1

smallest part of the chemical element that can exist is known as atom
a group of atom bonded together is known as molecule which represent the smallest unit of chemical compound that can take part in chemical reaction

Answer 2

the smallest particle of matter is called atom. the group of atoms that are bonded together is known as molecule. according to law of chemical combination mass can neither be created nor be destroyed. according to law of constant proportion , in a chemical substance the elements are in definite proportion by Thier masses.