Question

Carbon dioxide is a colorless odorless gas why is it considered a pollutant?

Answer 1

Carbon dioxide is a gas having chemical formula $CO_{2}$, a gas which exhaled by humans and inhaled by plants. It is also emitted from the sources such as cement production and combustion of fossil fuels. It is also known as greenhouse gas associated with acidification of ocean.

Carbon dioxide with other gases acts like a blanket of Earth which absorbs infrared radiations emitted from the sun and thus, preventing the escaping of these rays into the outer space which results in the gradual heating of Earth's surface and atmosphere i.e. increase in temperature of Earth. This process is known as Global Warming.

Hence, carbon dioxide is responsible for the increase in warming of the atmosphere i.e. option (D).

Answer 2

Even though carbon dioxide is a colorless, odorless gas, it is still considered a pollutant because D. it increases the warming of the atmosphere.
Global warming is the result of the abundance of carbon dioxide on Earth, which is why ecologists and environmentalists do everything in their power to raise awareness of this problem.