Question

which substance below has dipole-dipole forces?
f₂
ch₄
h₂s
co₂
none of the above

Explanation:

Dipole-dipole forces exist between polar molecules (permanent dipole moment).

• $\text{F}_2$: Nonpolar (same atoms, no electronegativity difference).
• $\text{CH}_4$: Nonpolar (tetrahedral symmetry cancels dipoles).
• $\text{H}_2\text{S}$: Polar (bent shape, electronegativity difference between S and H creates permanent dipoles).
• $\text{CO}_2$: Nonpolar (linear symmetry cancels dipoles).

Answer:

H₂S