Explanation

Hydrogen (H2) is not a greenhouse gas.

Greenhouse gases are gases in the Earth's atmosphere that absorb and emit radiation, trapping heat and contributing to the Greenhouse Effect.

The main greenhouse gases are:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Water vapor (H2O)
• Ozone (O3)
• Chlorofluorocarbons (CFCs)
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)

Explanation

French physicists Charles Fabry and Henri Buisson discovered the ozone layer in 1913.

They used an interferometer to measure the amount of ozone in the atmosphere.

Explanation

Lithium is the lightest metal.

It has the lowest density of all metals.

This making it the least dense metal element.

Explanation

• A Homogeneous mixture has the same proportion of its compound in a sample.
  • Sugar in water is a homogeneous mixture.
• A Heterogeneous mixture has a different proportion of its compound in a sample. 
• A Mixture in which a solute particle does not dissolve, but gets suspended is a suspension.
• A solution in which the substances are regularly suspended in a fluid is a Colloidal Solution.
• A true solution is a homogeneous mixture of two or more substances in which the substance dissolved in the solvent has a particle size of less than 10-9 m or 1 nm.

Explanation