Question

If I ml of water contains 20 drops. Then no. of molecules in a
drop of water is
(AFMC 2010]
(a) 6.023x10^' molecules (b) 1.376x1020 molecules
(c) 1.344x10'molecules (d) 4.346x1020 molecules​

Answer 1

density of water 1gm/ml
so 1ml=1gm
mol.mass of water =18 gm
so 1mg = 1/18 mole= 3.34 * 10^ 22 molecules
1 ml= 20 drops
1 drop= 1.67*10^21 molecules