Oxygen has an atomic number of 8. The n=1 energy level has two electrons, and the n = 2 energy level has six electrons. Oxygen's valence is . ● +2
● -2
● +1
● -1 ​

You want to cultivate some exotic plants at your farm. however, the climate is chillier than the temperature range favorable to the crop. which is the best method to use for the cultivation of this exotic crop? a. use a crop rotation method b. use a lot of fertilizer c. prepare the seed bed properly d. use a greenhouse e. use irrigation