Question 1

Which of the following statements best explains why all four C-H bonds in methane ($$CH_4) $$are identical in energy and length?

Accepted Answer

Because the carbon atom undergoes $$sp^3$$ hybridization, forming four equivalent hybrid orbitals.

Question 2

What is the bond angle in a molecule where the central atom is $$sp^2$$ hybridized?

Accepted Answer

$$120^\circ$$

Question 3

Which of the following molecules is expected to be nonpolar based on its geometry and hybridization?

Accepted Answer

Methane ($$CH_4$$), $$sp^3$$ hybridized

Question 4

A carbon atom in ethyne ($$C_2H_2) is $$involved in which type of hybridization, and what is the resulting geometry?

Accepted Answer

$$sp$$ hybridization; linear geometry

Question 5

Given the Lewis structure for formaldehyde ($$CH_2O$$), what is the hybridization of the central carbon atom?

Accepted Answer

$$sp^2$$

Question 6

Which of the following best describes the difference between a sigma ($$\sigma) $$and a pi ($$\pi) $$bond?

Accepted Answer

A $$\sigma$$ bond is stronger and allows free rotation, while a $$\pi$$ bond restricts rotation and is weaker.

Question 7

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in ethene ($$C_2H_4$$)?

Accepted Answer

5 $$\sigma$$ and 1 $$\pi$$

Question 8

Which of the following steps is NOT part of the process for drawing a Lewis structure?

Accepted Answer

Maximizing the number of unpaired electrons.

Question 9

What is the formal charge on the oxygen atom in the hydroxide ion ($$OH^-$$)?

Accepted Answer

$$-1$$

Question 10

Which of the following best explains why acetylene ($$C_2H_2) is $$used as a fuel in welding torches?

Accepted Answer

Its $$sp$$ hybridized carbons form a triple bond, releasing a large amount of energy upon combustion.

Question 11

Which of the following molecules contains a central atom with $$sp^3$$ hybridization and at least one lone pair of electrons?

Accepted Answer

Ammonia ($$NH_3)$$

Question 12

A molecule has a central atom with three sigma bonds and one lone pair. What is the expected geometry and hybridization?

Accepted Answer

Trigonal pyramidal, $$sp^3$$

Question 13

Which of the following is a correct calculation for the number of bonds in a molecule using the Lewis structure method?

Accepted Answer

$$E = (e-O - e-V)/2$$

Question 14

Which of the following atoms is most likely to carry a negative formal charge in a stable Lewis structure?

Accepted Answer

Oxygen

Question 15

Which of the following best describes the geometry and polarity of $$CO_2$$?

Accepted Answer

Linear and nonpolar

Question 16

How many lone pairs are present on the central oxygen atom in a water molecule ($$H_2O$$)?

Accepted Answer

2

Question 17

Which of the following is a structural isomer of ethanol ($$C_2H_6O$$)?

Accepted Answer

Dimethyl ether

Question 18

Which of the following statements about hybrid orbitals is correct?

Accepted Answer

$$sp^2$$ orbitals are 33.3% $$s$$ and 66.6% $$p in $$character.

Hybridization, Lewis Structures, and Molecular Geometry in Organic Chemistry

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