About one-third of the toxic metal, mercury (Hg), is released into the air from natural sources, such as rocks, soil, volcanoes, and the ocean. The remaining two-thirds come from human activities such as . a. airplane exhaust b. gold mining c. livestock farming d. automobile exhaust e. plastic recycling

Two-third of the toxic metal, mercury comes from gold mining.

Explanation:

During gold mining small pieces of gold which are within  the soil are separated with the help of mercury. Both gold and mercury are mixed and they forms amalgam. Further gold can be extracted by vaporizing the mercury, thus releasing it into air and contributing to two-third of the air pollution by human activities.

Therefore (d) gold mining is the correct answer.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.