Question

Dipole-induced dipole interactions are present in which of the following pairs ?

• A. H₂O and alcohol
• B. Cl₂ and CCI₄
• C. HCl and He atoms
• D. SiF₄ and He atoms

Answer 1

The Correct Option is C

To understand the type of interaction present between the given pairs of molecules, it is essential to grasp the concept behind dipole-induced dipole interactions. These interactions occur when a polar molecule (having a permanent dipole) causes a distortion in the electron cloud of a nearby non-polar molecule, thereby inducing a dipole in it.

• HCl and He atoms: HCl is a polar molecule with a permanent dipole due to a difference in electronegativity between hydrogen (H) and chlorine (Cl). Helium (He) is a noble gas and a non-polar atom. When the polar molecule HCl approaches the non-polar atom He, it induces a temporary dipole in the helium atom. This situation is a classic example of dipole-induced dipole interaction.
• H₂O and alcohol: Both water (H₂O) and alcohol have permanent dipoles because of the presence of O-H bonds. The interaction between these substances is primarily hydrogen bonding, not dipole-induced dipole.
• Cl₂ and CCl₄: Chlorine (Cl₂) is a non-polar molecule, and carbon tetrachloride (CCl₄) is also non-polar. The interactions here are weak London dispersion forces and do not involve dipole-induced dipole interactions.
• SiF₄ and He atoms: Silicon tetrafluoride (SiF₄) is a non-polar molecule because of its symmetrical tetrahedral structure. While helium atoms could be polarized, SiF₄ itself does not have a permanent dipole to induce any dipole in He atoms.

Given these points, the correct answer is the pair HCl and He atoms, where the dipole-induced dipole interactions occur.