If 1 mL of water contains 20 drops, the number of water molecules, in each drop of water, is (A is A

Question

If 1 mL of water contains 20 drops, the number of water molecules, in each drop of water, is (A is Avogadro number)

Accepted Answer

Sol. Key concept: Mass per drop gives moles per drop and then molecules.Taking the density of water as 1 g mL⁻¹, one millilitre has a mass of 1 g. If it consists of 20 drops, the average mass per drop is 1/20 = 0.05 g.$$n_{drop} = \frac{0.05}{18}\ mol$$$$N_{drop} = \frac{0.05}{18}A = \frac{A}{360} \approx 1.67 	imes 10^{21}$$The symbol A in the question denotes Avogadro’s constant. Hence option (d).

Question

Options

Solution

More Mole Concept Questions