Question 214, Meteorology - Quiz BPL Gas - Balloon Pilot License

Oxygen 78 % Water vapour 21 % Nitrogen 1 %
Oxygen 21 % Water vapour 78 % Noble gases / carbon dioxide 1 %
Nitrogen 21 % Oxygen 78 % Noble gases / carbon dioxide 1 %
Oxygen 21 % Nitrogen 78 % Noble gases / carbon dioxide 1 %