Question

Assertion: Helium and berylium having similar outer electronic configuration of type $ns^2$ .
Reason: Both are chemically inert.

• A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion
• B. If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion
• C. If Assertion is true but the Reason is false
• D. If both Assertion and Reason are false

Answer 1

Answer: (C)

Helium $: Z=2 ; \,\,\,\,\,\,1 s^{2}$

Berylium : $Z =4 ;\,\,\,\,\,\,\, 1 s ^{2}, 2 s ^{2}$

Helium is an inert gas while beryllium is reactive due to unfilled $2 p$ valence shells.