Question

the atomicity of carbon dioxide and water

Answer 1

co2 has the atomicity of 3 ...1 c atom n 2 o atoms
h2o also has the atomicity of 3 ....2 atoms of h n 1 atom of o 

Answer 2

As we know that,atomicity means number of atoms present in a molecule or compound.
So,
CO2=
1 atom of carbon+2 atom of oxygen
=3 atoms.
So,the atomicity of CO2 is 3.
H2O=
2 atom of hydrogen+1 atom of oxygen
=3 atoms.
So,the atomicity of H2O is 3.