22. Select two substances that do not have a molecular crystal lattice: 1) KNO_(3) 2) NH_(3) 3) BN 4) SO_(3) 5) C_(5)H_(12) Answer (score: 1)

The correct answer is 2) $NH_{3}$ and 5) $C_{5}H_{12}$.<br /><br />Molecular crystal lattices are formed by molecules held together by relatively weak intermolecular forces, such as van der Waals forces or hydrogen bonds. In this case, $NH_{3}$ and $C_{5}H_{12}$ are both molecular compounds, meaning they consist of discrete molecules rather than a lattice of ions or covalently bonded atoms.<br /><br />$NH_{3}$, or ammonia, is a simple molecule composed of one nitrogen atom bonded to three hydrogen atoms. It forms a molecular crystal lattice due to the weak hydrogen bonds between the molecules.<br /><br />$C_{5}H_{12}$, or pentane, is a hydrocarbon molecule composed of five carbon atoms bonded to twelve hydrogen atoms. It also forms a molecular crystal lattice due to the weak van der Waals forces between the molecules.<br /><br />On the other hand, $KNO_{3}$, BN, and $SO_{3}$ are all ionic or covalent compounds that form crystal lattices. $KNO_{3}$, or potassium nitrate, is an ionic compound that forms a lattice of potassium ions and nitrate ions. BN, or boron nitride, is a covalent compound that forms a lattice of boron atoms and nitrogen atoms. $SO_{3}$, or sulfur trioxide, is a covalent compound that forms a lattice of sulfur atoms and oxygen atoms.