Question

why do you think the noble gases are placed in a separate group???
answer in easy language

Answer 1

They are helium, neon, argon, krypton, xenon, and radon. They were once called inert gases because they were thought to be completely inert—unable to form compounds. This is a reasonable belief because the noble gases have a complete octet, making them very stable and unlikely to gain or lose any electrons.

Answer 2

Because if noble gases are placed in a separate group then it became helpful to learn easily and this is more helpful for the students