Question

The following questions are true/false

1. The potential energy associated with London dispersion interactions decreases with intermolecular distance as r-12 (where r is the intermolecular distance).

2. SiH4 is more polarizable than CH4.

3. In H2, the antibonding orbital formed by linear combination of two 1s orbitals has zero nodes.

4. In N2, the π bonding orbital formed by linear combination of two 2p orbitals has one node.

5. CO2 has zero total permanent dipole moment.

6. The kinetic energy of the electron in the H2+ molecule is higher than the kinetic energy of the electron in a hydrogen atom.

7. In valence bond theory, only aromatic molecules display resonance.

8. The bond order of the HeH+ molecule is zero.
9. HBr is a polar molecule.
10. An ion-dipole interaction is shorter range than a dipole-dipole interaction.

Answer 1

There are many subparts in this question I am answering first four subparts only (Chegg Policy: 1 questions per post or 4 sub parts in 1 question)

ANSWER:

1. FALSE => The Lennard-Jones equation considers the two forces that experiment a pair of neutral atoms or molecules. This equation has two terms, the first one (A/r12) describe the efecct of repulsion forces and the second one (B/r6) descrbe the effect of atraction forces. The potential energy associated to London dispersion interactions an atraction force, then, this potential energy varies with r6 not with r12

1. TRUE => Si is bigger than C, this means that valence electrons (which forms bonding with H) are farthest from the nucleus in the Si atom and electrons are less tightly held. Then, the Si-H bonds are weaker and more polarizable than C-H bond
2. FALSE => The combination of two 1s orbital, forms two molecular orbitals (one bonding MO and one antibonding MO). The bonding MO does not have any node, whereas the antibonding MO has one node

1. TRUE => The linear combination of two 2p orbital to form a pi orbital produces two pi orbitals (one bonding and one antibonding). The bonding MO have one nodal plane, whereas the antibonding MO has two nodal planes