Which gas contributes to global warming through its greenhouse effect?

Which one of the following statements is true with regard to a greenhouse?

The main component of greenhouse gases is

The relative contributions of carbon dioxide (CO₂), nitrous oxide (N₂O), chlorofluorocarbons (CFCs) and methane (CH₄) towards global warming are :

The use of plastics has led to a number of environment-related problems. For this, which one of the following statements is correct?

Methemoglobinemia is caused by the drinking of water contaminated with