Question

9. Assertion: For noblegases, valency is zero.
Reason: Noble gases have 8 valence electrons,​

Answer 1

Answer:

A is true but R is false

Explanation:

Noble gas has 8 electrons in outermost orbit

Answer 2

Here both assertion is correct but reason is not correct except helium all noble gas have 8 valence electrons.

• Noble gas are those elements of the periodic table that has completed valence electrons.
• Helium has atomic number 2 it has only 2 valence electrons in its outer most shell.
• Thus, the given reason is wrong.
• Noble gas have the tendency of no loose and gain of electron because they have completely full outer most shell
• For example Neon is a noble gas of atomic number 10.
• It's electronic configuration is 2,8.
• It has 8 electrons in its outer most shell and it has same valency because of completely filled outer most shell.
• The same concept will applicable on all the noble gases.

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