$$\text{Bond order} = \frac{\text{number of electrons in bonding MOs} - \text{number in antibonding MOs}}{2}$$

Question 1

Which statement best describes the concept of orbital hybridization in methane (CH$$_4$$)?

Accepted Answer

The carbon atom mixes one s and three p orbitals to form four equivalent sp$$^3$$ hybrid orbitals.

Question 2

According to Valence Bond Theory, what is required for a covalent bond to form between two atoms?

Accepted Answer

Half-filled atomic orbitals from each atom must overlap, accommodating two electrons of opposite spin.

Question 3

What is the bond angle in a molecule with sp$$^3$$ hybridization, such as CH$$_4$$?

Accepted Answer

$$109.5^\circ$$

Question 4

Which type of bond results from the 'end-to-end' overlap of atomic orbitals?

Accepted Answer

Sigma ($$\sigma) $$bond

Question 5

In BF$$_3$$, what is the hybridization of the boron atom?

Accepted Answer

sp$$^2$$

Question 6

Which statement correctly compares Molecular Orbital (MO) Theory and Valence Bond (VB) Theory?

Accepted Answer

VB Theory uses atomic orbitals calculated for atoms, while MO Theory uses molecular orbitals spread over the entire molecule.

Question 7

What is the bond order of the H$$_2$$ molecule according to Molecular Orbital Theory?

Accepted Answer

$$1$$

Question 8

Which of the following best explains why sp$$^2$$ hybridization leads to a trigonal planar geometry?

Accepted Answer

Three sp$$^2$$ hybrid orbitals arrange themselves $$120^\circ$$ apart in a plane to minimize electron pair repulsion.

Question 9

Which of the following molecules requires d orbital participation in hybridization?

Accepted Answer

SF$$_6$$

Question 10

A molecule has a bond order of zero according to MO theory. What does this indicate about the molecule?

Accepted Answer

It is unstable and does not exist under normal conditions.

Question 11

Which rule is used to assign electrons to molecular orbitals in MO theory?

Accepted Answer

Electrons fill the lowest energy molecular orbitals first, following Hund's rule and the Pauli exclusion principle.

Question 12

What is the main difference between a sigma ($$\sigma) $$bond and a pi ($$\pi) $$bond?

Accepted Answer

A sigma bond results from end-to-end overlap, while a pi bond results from side-to-side overlap.

Question 13

Which of the following is true about sp$$^3$$ hybrid orbitals?

Accepted Answer

They are formed by mixing one s and three p orbitals.

Question 14

Which molecule is best described by delocalized electrons in molecular orbitals according to MO theory?

Accepted Answer

NO

Question 15

What is the bond order formula in MO theory for a diatomic molecule?

Accepted Answer

$$	ext{Bond order} = \frac{	ext{number of electrons in bonding MOs} - 	ext{number in antibonding MOs}}{2}$$

Question 16

Which of the following best describes the electron distribution in a molecule according to MO theory?

Accepted Answer

Electrons are assigned to molecular orbitals delocalized over the entire molecule.

Question 17

Which hybridization is expected for the central atom in a molecule with a linear geometry?

Accepted Answer

sp

Question 18

Which of the following statements about hybrid orbitals is correct?

Accepted Answer

Hybrid orbitals are directed towards terminal atoms, maximizing overlap and bond strength.

Question 19

Which molecule would you expect to have sp$$^2$$ hybridization at the central atom?

Accepted Answer

BF$$_3$$

Question 20

Which of the following is a key advantage of MO theory over VB theory?

Accepted Answer

MO theory can describe molecules in excited states and those with delocalized electrons.

Chapter 6: Bonding and Molecular Structure – Orbital Hybridization and Molecular Orbitals

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