Question

1. what is a tool used to measure air pressure?
2. what is density?
3. what is the atmosphere made of and what does it do?
4. what is the gas that is made of three oxygen atoms?
5. define altitude:
6. what is it called when pollutants mix with fog?

Explanation:

1. A barometer is an instrument for measuring air - pressure.
2. Density is defined as mass per unit volume.
3. The atmosphere is mainly composed of nitrogen (about 78%), oxygen (about 21%), and small amounts of other gases like argon, carbon - dioxide, etc. It protects life on Earth by absorbing harmful radiation, regulating temperature, and providing oxygen for respiration.
4. The gas made of three oxygen atoms is ozone.
5. Altitude is the height above sea - level or a given reference point.
6. When pollutants mix with fog, it is called smog.

Answer:

1. A barometer.
2. Mass per unit volume.
3. Mainly nitrogen, oxygen, etc.; protects life, regulates temperature, provides oxygen.
4. Ozone.
5. Height above sea - level or a reference point.
6. Smog.