Question

Octet rule is not followed in

• A. CCU, \(N_2O_4\) and \(N_2O_5\)
• B. \(BF_3\), \(BeCl_2\) and \(NO_2\)
• C. NaCl, \(MgCl_2\), \(MgO\)
• D. \(PCl_3\), \(NH_3\), \(H_2O\)

Hint:

Octet rule exceptions include:
\textbf{Incomplete octet} (e.g., \(BF_3\), \(BeCl_2\))
\textbf{Odd-electron molecules} (e.g., \(NO_2\))
\textbf{Expanded octet} (e.g., \(PCl_5\), \(SF_6\))

Answer 1

The Correct Option is B

Step 1: The octet rule states that atoms tend to complete eight electrons in their valence shell to attain stability.
Step 2: In \(BF_3\), boron has only six electrons in its valence shell, hence it does not satisfy the octet rule.
Step 3: In \(BeCl_2\), beryllium has only four electrons in its valence shell, so the octet rule is not followed.
Step 4: In \(NO_2\), nitrogen has an odd number of electrons, making it impossible to complete an octet.
Step 5: The compounds in options (A), (C), and (D) follow the octet rule for their central atoms.