How many moles of oxygen are contained in one litre at S.T.P. of air if its volume content is 21% in air

How many moles of oxygen are contained in one litre at S.T.P. of air i

1.	How many moles of oxygen are contained in one litre at S.T.P. of air if its volume content is 21% in air
Answer» Solution :The volume of OXYGEN in 1 litre of air at S.T.R `=(1 xx 21)/100 = 0.21 L` `therefore` 22.4 L of oxygen at S.T.P. contain moles =1 `therefore 0.2 L` of oxygen at S.T.P. will contain moles `=1/(22.4) xx 0.21 = 9.4 xx 10^(-3)` Hence, ONE litre of air at S.T.R contains `9.4 xx 10^(-3)`moles of oxygen.