How many molecules of water and oxygen atoms are present in 0.9 g of water?

Explanation

Gram-molecular mass of water = 18 g
Number of moles in 0.9 g of water `=(0.9 )/(18 )=0.05`
Number of water molecules in one mole of water
`= 6.023xx 10^(23)`
Number of molecules of water in 0.05 moles
`=0.05 xx 6.023 xx 10^(23) = 3.010 xx 10^(22)`
As one molecule of water contains one oxygen atom, so, number of oxygen atoms in `3.010 xx 10^(22)` molecules of water `= 3.010 xx 10^(22)`