Lithium has 3 electrons. why do 2 electrons go in the first shell, and one in the second?

a) the electrons go randomly into shells.

b) the first shell only holds 2 electrons so the 3rd electron had to go in the second shell.

c) all the electrons could go into the second shell.

d) the shells appear and disappear so the electrons go anywhere.

B) The first shell only holds 2 electrons so the 3rd electron had to go in the second shell.

Explanation:

Electrons fill up from smallest to largest, the first electron shell only holds 2 electrons, so the remaining electron had to go to the second shell.

what have scientists found to be the most efficient and effective way to insert new sequences into an individual? a-scientists have created genetically altered foods that release dna during digestion. b-scientists use viruses to insert specific gene sequences. c-scientists irradiate genes so that they can be absorbed through the skin.

b. the carbon cycle ensures living things have a source of hydrogen