Which group of elements could be placed in mendeleev's periodic table without disturbing the original order ? Give reason.

Explanation

Noble gases group of elements can be placed in Mendeleev.s Periodic Table without disturbing the original order.
According to Mendeleev.s classification, the properties of elements are the periodic function Ans. (a) Element X is sulphur (atomic number 16) of their atomic masses and there is a periodic (b) K, L, M : 2, 8, 6 recurrence of elements with similar physical and chemical properties. Noble gas being inert, could be placed in a separate group without disturbing the original order.