Assertion - Sodium and aluminium have atomic numbers 11 and 13, respectively. They are separated by one element in the periodic table, and have valencies 1 and 3 respectively. Chlorine and potassium are also separated by one element in the periodic table (their atomic number being 17 and 19 respectively) and yet both have valency 1. Reason - Cl requires one electron to complete its octet and its valency is 1 while K has one electron in its outermost shell which it can easily lose to complete its octet and can attain the most balanced state after forming an octet. So, both have valency 1. A. Both assertion and reason are correct and reason is correct explanation of assertion B. Both assertion and reason are correct and reason is not correct explanation of assertion C. Assertion is correct but reason is incorrect D. Both assertion and reason are incorrect

Harshit Singh

4 Years agoGrade 12th pass