Question

Assertion :In the same period or subgroup a gradual change in a particular property may be seen Reason: The periodic repetition of the properties of the elements is due to the recurrence of similar valence shellelectronic configurations after certain regular intervals

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Periodicity :
The repetition of the properties of elements after regular intervals when the elements are arranged in the orderof increasing atomic number is called periodicity.
The periodic repetition of the properties of the elements is due to the recurrence of similar valence shellelectronic configurations after certain regular intervals. For example, alkalimetals have same valence shellelectronic configuration $n{s}^1$, therefore, have similar properties.