(C) The electronic configuration of $He$ is $1s^2$ and $Be$ is $1s^2 2s^2$. Both have $ns^2$ configuration,but helium is a noble gas and is chemically

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$(A)$ is correct but $(R)$ is incorrect.

(C) The electronic configuration of $He$ is $1s^2$ and $Be$ is $1s^2 2s^2$. Both have $ns^2$ configuration,but helium is a noble gas and is chemically inert because its valence shell $(1s)$ is completely filled. Beryllium is an alkaline earth metal and is reactive. Therefore,$(A)$ is correct but $(R)$ is incorrect.

Class 11 Chemistry s-Block Elements Alkaline earth metals

Easy

$Assertion$ $(A)$: Helium and beryllium have similar outer electronic configuration $ns^2$. $Reason$ $(R)$: Both are chemically inert.

AP EAMCET 2021 All AP EAMCET

A
Both $(A)$ and $(R)$ are correct and $(R)$ is the correct explanation of $(A)$.
B
Both $(A)$ and $(R)$ are correct but $(R)$ is not the correct explanation of $(A)$.
C
$(A)$ is correct but $(R)$ is incorrect.
D
Both $(A)$ and $(R)$ are incorrect.