Which of the following elements would lose an electron easily ?

Options

A. Mg
B. Na
C. K
D. Ca

Answer

C

Explanation

Electronic configuration of Mg (atomic number 12) 2,8,2
Electronic configuration of Na (atomic number 11) 2,8,1
Electronic configuration of K (atomic number 19) 2,8,8,1
Electronic configuration of Ca (atomic number 20) 2,8,8,2
From the above electronic configurations, it is clear that K and Na will lose electron easily to acheive stable configuration. But out of K and Na, K will lose electron more easily because to force of attraction on valence electron of K is least among the given. In oth words, larger the atomic radius of an element more easily it can lose its valence electron. Among all these, K has the largest atomic radius, therefore if can lose its valence electron more easily.
For atomic size refer to Q. 13.