STATES THAT FOR AN ATOM IN THE GROUND STATE, THE NUMBER OF UNPAIRED ELECTRONS IS THE MAXIMUM POSSIBLE AND THESE UNPAIRED ELECTRONS HAE THE SAME SPIN

Hund's rule

Explanation:

Hund's rule  states that for an atom in the ground state, the number of unpaired electrons is the maximum possible and these unpaired electrons have the same spin.

I will clearly illustrate this using the ground state of the nitrogen atom. Nitrogen atom contains seven electrons. Its electronic configuration is; 1s2 2s2 2px1 2py1 2pz1.

Notice that the number of unpaired electrons in this configuration is maximum and they are all expected to possess the same spin in accordance with Hund's rule .

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.