# Chapter 9 - Section 9.9 - Exceptions to the Octet Rule: Odd-Electron Species, Incomplete Octets, and Expanded Octets - Conceptual Connection - Page 411: 9.7

The correct answer is (b) $H_3PO_4$

#### Work Step by Step

Among the 4 given options, phosphorus ($P$) is the only third-period element. So, only $H_3PO_4$ can have an expanded octet. Second-period elements like carbon and nitrogen never form compounds with expanded octets.

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