Question

for which of the following compounds is hydrogen bonding the main intermolecular force?

bh₃

ch₄

hcn

ch₂f₂

ch₃nh₃

Explanation:

Hydrogen bonding requires a hydrogen atom bonded to N, O, or F (electronegative atoms with lone pairs).

• $\text{BH}_3$: B-H bonds are nonpolar; no H-bonding.
• $\text{CH}_4$: C-H bonds are nonpolar; no H-bonding.
• $\text{HCN}$: H is bonded to C (not N/O/F); no H-bonding.
• $\text{CH}_2\text{F}_2$: H is bonded to C (not F directly in a way that allows H-bonding as the main force); dipole-dipole is main.
• $\text{CH}_3\text{NH}_3$: H is bonded to N (electronegative with lone pairs), so hydrogen bonding is the main intermolecular force.

Answer:

CH₃NH₃