Question 1

Liquid oxygen is attracted to a magnetic field, as shown in the image. Which molecular property of O$$_2$$ explains this behavior?

Accepted Answer

O$$_2 is $$paramagnetic due to the presence of unpaired electrons in its molecular orbitals.

Question 2

According to the interaction energy diagram for two hydrogen atoms, what does the minimum point on the curve represent?

Accepted Answer

The bond length and bond energy of the H$$_2$$ molecule.

Question 3

The observed bond angle in methane (CH$$_4) is 109.5$^	ext{o}$$, but the theoretical prediction using unhybridized atomic orbitals is 90$$^	ext{o}. $$What concept resolves this discrepancy?

Accepted Answer

sp$$^3$$ hybridization of carbon's orbitals

Question 4

Which of the following best describes a sigma ($$\sigma) $$bond?

Accepted Answer

A head-to-head overlap of orbitals along the bond axis.

Question 5

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in a molecule of formaldehyde (H$$_2CO$$)?

Accepted Answer

3 $$\sigma$$, 1 $$\pi$$

Question 6

Which hybridization is associated with a linear geometry and a bond angle of 180$$^	ext{o}$$?

Accepted Answer

sp

Question 7

In the molecule C$$_2H$_2 ($$ethyne), what is the hybridization of each carbon atom and how many $$\pi$$ bonds are present?

Accepted Answer

sp; 2 $$\pi$$ bonds

Question 8

Which of the following molecules has sp$$^3d$^2$$ hybridization at the central atom?

Accepted Answer

SF$$_6$$

Question 9

According to molecular orbital (MO) theory, which of the following statements is true?

Accepted Answer

A molecule is stable if it has more electrons in bonding orbitals than in antibonding orbitals.

Question 10

What is the bond order of F$$_2$$ according to molecular orbital theory?

Accepted Answer

$$1$$

Question 11

Which of the following molecules is predicted to be paramagnetic based on its molecular orbital diagram?

Accepted Answer

O$$_2$$

Question 12

Which of the following has the shortest bond length according to molecular orbital theory?

Accepted Answer

N$$_2$$

Question 13

Which of the following best describes the difference between constructive and destructive interference in molecular orbital theory?

Accepted Answer

Constructive interference leads to bonding orbitals; destructive interference leads to antibonding orbitals.

Question 14

Which of the following statements about resonance and hybridization is correct?

Accepted Answer

Resonance involves delocalization of electrons, often in systems with sp$$^2$$ hybridized atoms.

Question 15

Which of the following is true about the rotation around single and double bonds?

Accepted Answer

Single bonds (sigma) allow free rotation, while double bonds (sigma + pi) restrict rotation.

Question 16

Which hybridization scheme and geometry is expected for the central atom in AsF$$_5$$?

Accepted Answer

sp$$^3d$$; trigonal bipyramidal

Question 17

Which of the following best explains why the bond order of O$$_2 is $$less than that of N$$_2$$?

Accepted Answer

O$$_2$$ has more electrons in antibonding orbitals than N$$_2.$$

Question 18

Which of the following statements about molecular orbital diagrams for B$$_2$$, C$$_2$$, and N$$_2 is $$correct?

Accepted Answer

For B$$_2$$, C$$_2$$, and N$$_2$$, the $$\pi_{2p}$$ orbitals are lower in energy than the $$\sigma_{2p}$$ orbital.

Question 19

Which of the following best describes the bond order calculation in molecular orbital theory?

Accepted Answer

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

Valence Bond Theory, Hybridization, and Molecular Orbital Theory: Study Notes for General Chemistry

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