H2 is present in air then why it forms an explosive mixture with air when it is collected by downward displacement of air IN LABORATORY PREPARATION OF H2
Hydrogen is mostly present in molecules such as water and organic compounds on Earth.In air it is present in very minute concentration due to which it doesnot form an explosive mixture with air.In the laboratory, the amount (concentration) of hydrogen gas produced is high due to which it forms an explosive mixture with air.