<u>Answer:
</u>
The build-up of three oxygen created our ozone layer around two billion years ago.
<u>Explanation:
</u>
- The ozone layer is a part of the stratosphere which is located right after the troposphere in the atmosphere of the Earth.
- The ozone gas is made up of the abundance of three oxygen molecules combining with the ultraviolet radiation emitted by the Sun.
- The development of the ozone layer happened around two billion years ago when the oxygen concentration levels on the planet began to rise slowly and gradually.
Answer:
b. Tall oak trees
Explanation:
In order for the owner to be able to have energy benefit for the home in a place with hot summers and cold winters, the most practical thing would be to have tall oak trees in front of the large glass windows on the southern side. The reason for this is that the oak trees will be beneficial in both seasons. During the hot summers, the oak trees will provide a lot of shade, thus lowering the temperature on the southern side where the large glass windows are. During the winter, the oak trees will have no leafs on them, meaning that the southern side will be able to get the needed sunlight in this period. We come to a situation where the oak trees will reduce the energy spending for cooling down in the summer, and it will reduce the energy spending for warming up in the winter.
Answer:
I think the ans is option no. B
