Question 1

Which of the following elements is most likely to form four covalent bonds in organic molecules, according to the octet rule and the study materials?

Accepted Answer

C

Question 2

According to the Aufbau principle, which electron configuration is correct for a neutral carbon atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 3

Which of the following statements about electronegativity is TRUE based on the periodic trend shown in the notes?

Accepted Answer

Electronegativity decreases down a group and increases across a period.

Question 4

Which of the following best describes a nonbonding electron pair in a Lewis structure?

Accepted Answer

A pair of electrons not involved in bonding, localized on a single atom.

Question 5

Given the molecule $$\mathrm{CH_3OH} ($$methanol), how many lone pairs are present on the oxygen atom in its Lewis structure?

Accepted Answer

2

Question 6

Which of the following is the correct formal charge on the nitrogen atom in the cyanide ion ($$\mathrm{CN^-}$$)?

Accepted Answer

$$0$$

Question 7

Which of the following molecules is expected to have the most polar bond?

Accepted Answer

$$\mathrm{H-F}$$

Question 8

Which of the following is an exception to the octet rule as described in the notes?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 9

What is the correct order of increasing bond polarity for the following bonds: $$\mathrm{C-H}$$, $$\mathrm{C-F}$$, $$\mathrm{C-Cl}$$?

Accepted Answer

$$\mathrm{C-H} \u003c \mathrm{C-Cl} \u003c \mathrm{C-F}$$

Question 10

Which of the following best explains why $$\mathrm{O_2$} is $$not a polar molecule, even though the $$\mathrm{O-O}$$ bond is between two highly electronegative atoms?

Accepted Answer

The molecule is linear and the bond dipoles cancel.

Question 11

According to the study materials, which of the following is the correct definition of a Bronsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$\mathrm{H^+}).$$

Question 12

Which of the following electron configurations represents an excited state of a carbon atom?

Accepted Answer

$$1s^2$$\ $$2s^1$$\ $$2p^3$$

Question 13

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

Accepted Answer

A $$\sigma$$ bond is formed by head-on overlap of orbitals, while a $$\pi$$ bond is formed by side-on overlap.

Question 14

If a molecule has a central atom with 4 bonds and 0 lone pairs, what is its expected geometry?

Accepted Answer

Tetrahedral

Question 15

Which of the following is the correct calculation for the formal charge on the oxygen atom in the hydroxide ion ($$\mathrm{OH^-}$$)?

Accepted Answer

$$6 - 1 - 6 = -1$$

Question 16

Which of the following best explains why $$\mathrm{H_2O} is a $$polar molecule?

Accepted Answer

The molecule is bent and the bond dipoles do not cancel.

Question 17

Which of the following is the correct electron configuration for a neutral nitrogen atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^3$$

Question 18

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures represent different possible locations of electrons, not atoms.

Question 19

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are the electrons in the outermost shell and are involved in forming bonds.

Atomic Structure, Bonding, and Electronegativity in Organic Chemistry

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