Answer:
The 3p orbitals have the same general shape and are larger than 2p orbitals, but they differ in the number of nodes. You have probably noticed that the total number of nodes in an orbital is equal to n−1 , where n is the principal quantum number. Thus, a 2p orbital has 1 node, and a 3p orbital has 2 nodes.
Answer is: the discovery of sub atomic particles like electrons.
J. J. Thomson discovered the electron in 1897.
His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge.
With this model, he abandoned his earlier hypothesis (the atom was composed of immaterial vortices).
J.J. Thomson placed two oppositely charged electric plates around the cathode ray. He did experiments using different metals as electrode materials and found that the properties of the cathode ray remained constant no matter what cathode material he used.
Tomson concluded that atoms are divisible and that the corpuscles are their building blocks (atoms are made up of smaller particles).
Inert means unreactive in nature or un reactive in there normal or natural state
and noble gas has there outermost shell electron filled up they complete there duplet or oclet valency state that why there inert in there natural state