Answer:
1. Form of oxygen that combines three oxygen atoms into each molecule is called ozone.
2. Most important weather phenomena occur in the troposphere.
Explanation:
1. The form of oxygen which combines with three oxygen atoms has a molecular formula as which is known as ozone.
Therefore, form of oxygen that combines three oxygen atoms into each molecule is called ozone.
2. The lower part of the atmosphere also known as troposphere is a layer where almost all the weather phenomena occurs.
This layer contains 99% of total mass of water vapor and aerosols. Also, it contains about 75% of atmosphere's mass.
Therefore, we can conclude that most important weather phenomena occur in the troposphere.