Assertion :The Modern Periodic Table has 7 horizontal rows known as periods. Reason: The atoms of different elements which have the same number of occupied shells are placed in the same period. A period indicates the principal quantum number of the outermost shell of an element.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Both Assertion and Reason are incorrect

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
The Modern periodic table has 7 horizontal rows known as periods. The atoms of different elements which have the same number of occupied shells are placed in the same period. A period indicates the principal quantum number of the outermost shell of an element. The atomic number increases by one unit on moving from left to right in a period.

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