1) Which of the following molecular solids will exhibit dipole-dipole intermolecular forces: NH3, BF3, I2 and H2S?

a) NH3, and H2S (correct)
b) NH3, BF3, and H2S (BF3 has polar bonds, but is a nonpolar molecule)
c) I2 only
d) BF3 and I2
e) NH3, BF3, I2 and H2S

I think that either answer B or E is correct, im just not sure about I2. Please help!!

Hannah, I don't now how to answer this.

NH3, BF3 and H2S are gases at normal temperature. I2 is the only solid listed.

It's A because NH3 and H2S are the only ones that have lone pairs and that means they are polar. BF3 have no lone pair so it's nonpolar and I2 is nonpolar so dipole-dipole intermolecular forces are between polar molecules

To determine which of the given molecular solids will exhibit dipole-dipole intermolecular forces, we need to consider the polarity of the molecules.

NH3 (ammonia) and H2S (hydrogen sulfide) both have polar bonds due to the difference in electronegativity between the atoms. The nitrogen and sulfur atoms are more electronegative than the hydrogen atoms, causing a partial negative charge on the nitrogen and sulfur atoms and a partial positive charge on the hydrogen atoms.

On the other hand, BF3 (boron trifluoride) is a nonpolar molecule despite having polar bonds. This is because the fluorine atoms are arranged symmetrically around the central boron atom, resulting in a molecule with no overall dipole.

I2 (iodine) is also a nonpolar molecule, as the two iodine atoms are identical and have the same electronegativity. Therefore, there is no separation of charge and no dipole moment.

Based on this information, the correct answer is option a) NH3 and H2S, as these are the only molecules that have dipole moments and can exhibit dipole-dipole intermolecular forces.

To determine which of the molecular solids will exhibit dipole-dipole intermolecular forces, we need to analyze the polarity of each molecule.

First, let's consider NH3 (ammonia). NH3 has a trigonal pyramidal molecular geometry and a lone pair on the nitrogen atom. The N-H bonds are polar due to the difference in electronegativity between nitrogen and hydrogen. The asymmetry of the molecule makes NH3 polar, and it exhibits dipole-dipole intermolecular forces.

Next, BF3 (boron trifluoride) has a trigonal planar molecular geometry. Although the B-F bonds are polar, the molecular shape of BF3 is symmetrical, resulting in the cancellation of the dipole moments. Therefore, BF3 is a nonpolar molecule and does not exhibit dipole-dipole intermolecular forces.

Moving on to I2 (diiodine), I2 has a linear molecular geometry with a nonpolar covalent bond between the two iodine atoms. The molecule is symmetrical with the same electronegativity between the two iodine atoms, so it also does not exhibit dipole-dipole intermolecular forces.

Lastly, H2S (hydrogen sulfide) has a bent molecular geometry similar to water (H2O). The S-H bonds are polar, and the molecule is asymmetrical, making H2S polar. Therefore, H2S exhibits dipole-dipole intermolecular forces.

Based on this analysis, the correct answer is option a) NH3, and H2S. Only NH3 and H2S are polar molecules among the given options and exhibit dipole-dipole intermolecular forces.