Question: how many molecules of co2 are present in 1 litre of air?
Answer: Volume content of air is 0.03 means that 100 parts by volume of air contains 0.03 parts of CO2 by volume. So, 1 litre of air will contain 0.0003 litres of CO2. We know that at NTP 22.4 litres of CO2 contains one mole of CO2 i.e.- 6.022 * 10^23 number of molecules.