4. Answer in brief a) What is a greenhouse?
b) Name the main greenhouse gases,
c) What would happen if there was no greenhouse effect?
d) What are the three Rs that we need to use in our daily lives? kiya aap log en questions ka answer jante hai please sahi sahi batana ok​

a) A greenhouse is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.

b) The main greenhouse gases are Water vapor, Carbon dioxide, Methane, Ozone, Nitrous oxide and Chlorofluorocarbons.

c)Without the greenhouse effect, the Earth would have an average temperature of -18 °C and be covered in ice. Life as we know it would not be able to survive

d) The three R's that we need to use in our daily lives are reduce, reuse and recycle.