Question

The number of molecules from the following which contain only two lone pair of electrons is _____ .
\(H_2O, N_2, CO, XeF_4, NH_3, NO, CO_2, F_2\)

Answer 1

Correct Answer: 4

Analyzing the lone pairs of electrons in the given molecules. 
\(H_2O\): Oxygen has 2 lone pairs, and each hydrogen atom has 0 lone pairs. Total = 2 lone pairs. 
\(N_2\): Nitrogen in \(N_2\) has no lone pairs in the molecular structure. Total = 0 lone pairs. 
\(CO\): Carbon in CO has no lone pairs, but oxygen has 2 lone pairs. Total = 2 lone pairs. 
\(XeF_4\): Xenon in \(XeF_4\) has 2 lone pairs, and each fluorine atom has 3 lone pairs. Total = 2 lone pairs. 
\(NH\_3\): Nitrogen in \(NH_3\) has 1 lone pair, and each hydrogen atom has 0 lone pairs. Total = 1 lone pair. 
\(NO\): Nitrogen in NO has 1 lone pair, and oxygen has 2 lone pairs. Total = 3 lone pairs. 
\(CO_2\): Carbon in \(CO_2\) has no lone pairs, and oxygen has 2 lone pairs on each oxygen atom. Total = 4 lone pairs. 
\(F_2\): Each fluorine atom in \(F_2\) has 3 lone pairs. Total = 3 lone pairs. From the analysis, the molecules that contain only 2 lone pairs are \(H_2O\), \(CO\), and \(XeF_4\). 
Therefore, the correct answer is 4 molecules.