Question

Which of the following statements are correct? 
A. The process of the addition an electron to a neutral gaseous atom is always exothermic 
B. The process of removing an electron from an isolated gaseous atom is always endothermic 
C. The 1st ionization energy of the boron is less than that of the beryllium 
D. The electronegativity of C is 2.5 in $ CH_4 $ and $ CCl_4 $ 
E. Li is the most electropositive among elements of group 1 
Choose the correct answer from the options given below

• A. B and C only
• B. A, C and D only
• C. B and D only
• D. B, C and E only

Hint:

Review the definitions of electron affinity, ionization energy, electronegativity, and electropositivity. Consider the electronic configurations and trends in the periodic table.

Answer 1

The Correct Option is A

• [(A)] The addition of an \( e^- \) to a neutral gaseous atom is not consistently exothermic; it can be either exothermic or endothermic.
• [(B)] Be: 1s²2s²
  B: 1s²2s²2p¹
  In Be, the 2s subshell is completely filled. Therefore, more energy is required to remove an \( e^- \) when compared to B.
• [(D)] In \( CCl_4 \), due to the partial positive charge, \( Z_{eff} \) increases. Thus, the electronegativity (EN) of C in \( CCl_4 \) is greater than in \( CH_4 \): \( CCl_4>CH_4 \).
• [(E)] Cs is the most electropositive element.