Question

What is the colour of NO2 gas?

Answer 1

Nitric oxide is a colorless, flammable gas with a slight odor. Nitrogen dioxide is a deep red-orange gas that is poisonous but not flammable. It, along with aerosols, is responsible for the reddish-brown color of smog. At high concentrations it is highly toxic, and can cause serious lung damage.
NO2 is brown in colour.

Answer 2

Nitric oxide is a colorless, flammable gas with a slight odor. Nitrogen dioxide is a deep red-orange gas that is poisonous but not flammable. It, along with aerosols, is responsible for the reddish-brown color of smog. At high concentrations it is highly toxic, and can cause serious lung damage.