which of the following elements has the smallest ionization energy? choose 1 answer: a mg b si c cl

Explanation:

Step1: Recall ionization - energy trend

Ionization energy increases across a period from left - to - right in the periodic table. This is because the effective nuclear charge increases, making it harder to remove an electron.

Step2: Locate elements in periodic table

Mg (magnesium) is in Group 2 and Period 3, Si (silicon) is in Group 14 and Period 3, and Cl (chlorine) is in Group 17 and Period 3.

Step3: Compare positions

Since Mg is the left - most among the three elements in the same period (Period 3), it has the smallest effective nuclear charge among them for the outermost electrons. So, Mg has the smallest ionization energy.

Answer:

A. Mg