Question

Calculate the number of atom in 1.8 gm of H2O

Answer 1

here is your answer

molecular mass of water is 1*2+16=18u

hence gram molecular mass of water is 18gram

so no. of atoms in 18gram of water=1 mol so molar mass of water is 1 8gram/mol and by the formula

no of moles =mass of given substance/molar mass

we get 1.8/18 =1/10 moles

=no of atoms in 1/10 moles =1/10*6.022*10^23

=6.022*10^22