Question

Total number of atoms in 18 amu of H2O is:
(1) 3
(2) 3/NA
(3)NA
(4) 3NA​

Answer 1

option (4) 3NA

number of moles of H2O=  18g/18g/mol =1mol

now one mole of water contains 6.022×10  ∧23 molecules.

but, there are three atoms in H2 O molecule.

Therefore, number of gram atoms is 3NA

where NA =6.022×10  ∧23