Question

calculate the no. of water molecules and no. of oxygen and hydrogen atoms in a drop of water containing 0.03 mol of water

Answer 1

Number of water molecules in 0.03 mol of water = 0.03 x 6.022 x 1023 = 1.8 x 1022molecules of water.
1 water molecule(H2O) contain 1 oxygen atoms.
So, number of oxygen atoms in 0.03 mole of water = 0.03 x 6.022 x 1023 = 1.8 x 1022atoms of oxygen.
1 water molecule(H2O) contain 2 hydrogen atoms.
So, number of hydrogen atoms in 0.03 mole of water = 2 x 0.03 x 6.022 x 1023 = 3.6 x 1022 atoms of hydrogen

Answer 2

Number of water molecules in 0.03 mol of water = 0.03 x 6.022 x 1023 = 1.8 x 1022molecules of water. 

number of oxygen atoms in 0.03 mole of water = 0.03 x 6.022 x 1023 = 1.8 x 1022 atoms of oxygen.  

number of hydrogen atoms in 0.03 mole of water = 2 x 0.03 x 6.022 x 1023 = 3.6 x 1022atoms of hydrogen