Question

The five successive ionization enthalpies of an element are$800,2427,3658,25024,\mathrm{and}32824\mathrm{kJ}{\mathrm{mol}}^{-1}$. The number of valence electrons in the element is:

• A. $2$
• B. $4$
• C. $3$
• D. $5$

Answer 1

The correct option is C

$3$

The correct option is (C):

The Explanation of the correct option:

(C)

• Explanation: ${\mathrm{X}}^{+3}$ has a stable inert gas configuration due to the large jump after. So we have valence electrons.
• The fourth and fifth are extremely high (periodic properties), implying the presence of three valence shell electrons.
• The element contains three valence electrons.
• Diagram:

The Explanation of the incorrect option:

(A)

• Explanation: Because of the large jump after, ${\mathrm{X}}^{+3}$ has a reliable inert gas configuration.
• The second is extremely low (periodic properties), indicating the presence of three valence shell electrons.
• There are two valence electrons in the element.
• Diagram:

(B)

• Explanation: ${\mathrm{X}}^{+3}$ has a reliable inert gas configuration due to the significant drop after.
• The fourth which indicates the presence of three valence shell electrons very high (periodic properties).
• There are four valence electrons in the object.
• Diagram:

(D)

• Explanation: Due to the general obvious significant jump after, ${\mathrm{X}}^{+3}$ has a reliable inert gas configuration.
• The fifth, indicating the presence of three valence shell electrons, is extremely high (periodic properties).
• The element has a total of five valence electrons.
• Diagram:

Hence, the correct option is (c): The element contains three valence electrons.