Assertion (A): Alkali metals do not form dipositive ions.

Reason (R): After loss of one electron alkali metals achieve stable electronic configuration of noble gases.

1. Both A and R are true and R is the correct explanation of A
2. Both A and are true but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true

Both A and R are true and R is the correct explanation of A

Reason — Alkali metals (such as lithium, sodium, and potassium) do not form dipositive ions. Instead, they form monovalent cations by losing one electron. This is because they have a single electron in their outermost shell, and losing this one electron achieves the stable noble gas configuration.