Question
The electronic configurations of elements are as- A = 1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 4s^2 B = 1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^5 Which of the following is formula of ionic compound that could be formed between these two elements A and B?
MHT CET
Chemistry
Structure of Atom
2026
MHT CET 2026 (13 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. A _2 B
- B. AB _2
- C. AB _5
- D. A _5 B _2
Answer
B. AB _2
Step-by-step solution
Element A has the electronic configuration 1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 4s^2. It has 2 valence electrons in its outermost shell, so it loses 2 electrons to achieve a stable noble gas configuration, forming the A ^ 2+ ion. Element B has the electronic configuration 1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^5. It has 7 valence electrons in its outermost shell, so it gains 1 electron to achieve a stable noble gas configuration, forming the B ^ - ion. To form a neutral ionic compound, one A ^ 2+ ion combines with two B ^ - ions. The formula of the compound is AB _2. Answer: AB _2
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