Directions: Each of these questions contains an Assertion followed by a reason. Read them carefully and answer the question on the basis of the following options. You have to select the one that best describes the two statements.
Assertion: Group I (1s) elements are known as the alkali elements.
Reason: s-orbital can accommodate only two electrons.

If both assertion and reason are correct and the reason is the correct explanation of Assertion.

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If both assertion and reason are correct, but the reason is not the correct explanation of Assertion.

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If the assertion is correct but the reason is incorrect.

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If the assertion is incorrect but the reason is correct.

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Solution

The correct option is B
If both assertion and reason are correct, but the reason is not the correct explanation of Assertion.

Explanation of assertion:
The elements of group 1 are lithium(Li), sodium(Na), potassium(K), rubidium(Rb), cesium(Cs), and francium(Fr).
They all have 1 valence electron.
They are collectively known as alkali metals because they form hydroxides with water which are strongly alkaline.
Explanation of reason:
According to Pauli’s exclusion principle, an s-orbital contains at most two electrons with the opposite spin (up and down). s−orbital can accommodate only two electrons. A p-orbital can accommodate six electrons, a d orbital can accommodate 10 electrons, and an f-orbital can accommodate 14 electrons.
Hence, If both assertion and reason are correct, but the reason is not the correct explanation of Assertion.
Hence the correct option is B.

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Similar questions

Q. Assertion :Group I (

1 s

) elements are known as the alkali elements. Reason:

S -

orbital can accommodate only two electrons.

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