The correct answer is D. NO2.
Nitric acid is a strong acid that is commonly used in laboratories and industry. It is a colorless liquid that turns yellow when it is exposed to air. The yellow color is due to the presence of nitrogen dioxide, NO2. Nitrogen dioxide is a gas that is formed when nitric acid reacts with oxygen in the air. It is a poisonous gas that can cause respiratory problems.
The other options are incorrect. N2O is nitrous oxide, a colorless gas that is used as an anesthetic. NO is nitric oxide, a colorless gas that is produced by the body and plays a role in blood circulation. N2O5 is dinitrogen pentoxide, a white solid that is used as a fertilizer.
Here is a more detailed explanation of each option:
- N2O is nitrous oxide, a colorless gas that is used as an anesthetic. It is also known as laughing gas because it can cause people to laugh when they inhale it. Nitrous oxide is not responsible for the yellow color of nitric acid.
- NO is nitric oxide, a colorless gas that is produced by the body and plays a role in blood circulation. It is also a free radical, which means that it has an unpaired electron. Nitric oxide is not responsible for the yellow color of nitric acid.
- N2O5 is dinitrogen pentoxide, a white solid that is used as a fertilizer. It is also known as nitric anhydride. N2O5 is not responsible for the yellow color of nitric acid.
- NO2 is nitrogen dioxide, a gas that is formed when nitric acid reacts with oxygen in the air. It is a poisonous gas that can cause respiratory problems. Nitrogen dioxide is responsible for the yellow color of nitric acid.