Question

justify the statement "carbon di oxide is necessary for life on Earth"why we consider it as pollutent

Answer 1

Plants require CO2 in an optimum amount for the process of photosynthesis. But, increasing concentration
of (more than normal) CO2 is harmful and considered as a pollutant. Higher concentration of CO2 is one of the causes of greenhouse effect and global warming as it absorbs the infrared radiations thus increasing the temperature of Earth. This leads to many environmental problems.
Such as melting of ice
Sea level rise