Question

	1st Ionization Energy (eV)	2nd Ionization Energy (eV)
U	5.6	5.6
V	1.7	2.9
X	1.1	13.6
Y	12.4	2.8
Z	2.9	1.7

From the information given in the which of the following is most probably a Group IA metal?

• A. U
• B. V
• C. W
• D. X
• E. Y
• F. Z

Answer 1

Answer: (D)

X

Option D is the correct answer.

Group 1A elements have only one electron in their outermost shell. When it is ionized for the first time, the element tries to attain their nearest stable octet structure by removing this electron.

Thus very less amount of energy is required to remove the only one outermost electron. Hence first ionization energy is less.

After it attains the stable octet structure, it is very very difficult to remove the next electron from its outermost orbit beacuse now it is very stable and hence the second ionization energy is very high. This is satisfied by the element $X$