Question

Which group of elements could be placed in Mendeleev’s periodic table later on, without disturbing the original order ? Give reason.

Lakhmir Singh Chemistry Class 10

Answer 1

Ans: Noble gas elements like helium(He),Neon(Ne) and Argon(Ar) could not be placed in Mendeleev's periodic table because these gases were discovered very late and they are very inert and also present in extremely low concentrations in our atmosphere.