Question

find the number of atoms in the following ​

Answer 1

Answer:

Co2 is having one atom of carbon and two atom of oxygen

3NaCl is having three atom of sodium and three of chlorine

NH3 is having one atom of nitrogen and three atoms of hydrogen

Answer 2

Mass → Moles and Moles → Atoms.
196.967 u . ...
So, if you are given the mass of an element, you use the periodic table to find its molar mass, and multiply the given mass by the reciprocal of the molar mass. ...
Once you have moles, multiply by Avogadro's number to calculate the number of atoms.