Question

assertion magnesium belong to 3rd period of modern periodic table reason the valency electrons of magnesium is 2 option a both a and r are true and r is correct explanation of option b the the both a and r are true but are is not correct explanation for a​

Answer 1

Answer:

a)  Both A and R are true and R is the correct explanation of A.

Hope it helps

Answer 2

Answer:

Option (b) Assertion and Reason are true but reason is not correct explanation of assertion.

Explanation:

Assertion: Magnesium belongs to 3rd period of the modern periodic table.

The atomic number of Magnesium is 12, so its electronic configuration has to be- 2, 8, 2. The number of shells in an atom tell us the period number. Magnesium has 3 shells in its atom; hence, its period number is 3.

Reason: The valency electrons of Magnesium is 2.

The number of electrons in the valence shell tells us the group number. Magnesium has 2 electrons in its outermost shell, so its group number is 2.

The reason does not explain the assertion at all.

Conclusion:

Assertion and Reason are true but reason is not correct explanation of assertion.