LIFE SCIENCE

Detailed explanation-1: -Most of the elements important in biology need eight electrons in their outermost shell in order to be stable, and this rule of thumb is known as the octet rule. Some atoms can be stable with an octet even though their valence shell is the 3n shell, which can hold up to 18 electrons.

Detailed explanation-2: -The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds.

Detailed explanation-3: -Since all noble gases have 8 electrons in their valence shell and they are observed to be highly stable and inert, i.e., do not react with other elements. Thus, the octet rule sticks with filling of 8 electrons in the valence shell of an atom. Elements with less than 8 electrons in valence shell means less stable.

Detailed explanation-4: -Noble gases are the members of group 18 of the modern periodic table which are He, Ne, Ar, Kr, Xe and Rn.