Question 1

Which of the following best describes the octet rule as it applies to chemical bonding?

Accepted Answer

Atoms transfer or share electrons to obtain outer shells with eight electrons.

Question 2

What is the correct Lewis structure for a phosphorus atom?

Accepted Answer

A 'P' symbol surrounded by five dots, one on each side and one paired.

Question 3

Which of the following compounds is predicted by Lewis theory to have a linear molecular geometry?

Accepted Answer

$$\mathrm{CO}_2$$

Question 4

How many valence electrons are present in an oxygen atom, and how is this represented in its Lewis structure?

Accepted Answer

6 valence electrons, represented as six dots around the 'O' symbol.

Question 5

Which of the following best explains why water ($$\mathrm{H}_2\mathrm{O}) is a $$polar molecule?

Accepted Answer

The molecule has polar bonds and a bent geometry, so the dipole moments do not cancel.

Question 6

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity increases across a period and decreases down a group.

Question 7

What is the correct Lewis structure for the cyanide ion ($$\mathrm{CN}^-$$)?

Accepted Answer

A triple bond between C and N, each with a lone pair, enclosed in brackets with a negative charge.

Question 8

Which molecule has a trigonal planar geometry according to VSEPR theory?

Accepted Answer

$$\mathrm{H}_2\mathrm{CO}$$

Question 9

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally due to a difference in electronegativity.

Question 10

A molecule of ammonia ($$\mathrm{NH}_3) $$has four electron groups around the central atom. What is its molecular geometry?

Accepted Answer

Trigonal pyramidal

Question 11

Which of the following is an example of a molecule with resonance structures?

Accepted Answer

Ozone ($$\mathrm{O}_3)$$

Question 12

Which of the following best explains why oil and water do not mix?

Accepted Answer

Water is polar and oil is nonpolar, so water molecules attract each other and exclude oil molecules.

Question 13

Which of the following elements is the most electronegative?

Accepted Answer

Fluorine

Question 14

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

$$\mathrm{CO}_2$$

Question 15

Which of the following is the correct order of bond polarity from least to most polar?

Accepted Answer

Cl–Cl \u003c H–Cl \u003c Na–Cl

Question 16

Which of the following is a correct statement about the Lewis structure of methane ($$\mathrm{CH}_4$$)?

Accepted Answer

It has four single bonds arranged in a tetrahedral geometry.

Question 17

Which of the following is an exception to the octet rule?

Accepted Answer

Boron in $$\mathrm{BF}_3$$

Question 18

What is the bond angle in a molecule with a tetrahedral geometry?

Accepted Answer

$$109.5^\circ$$

Question 19

Which of the following best describes the difference between electron geometry and molecular geometry?

Accepted Answer

Electron geometry considers all electron groups, while molecular geometry considers only the arrangement of atoms.

Question 20

Which of the following steps is NOT part of writing a Lewis structure for a polyatomic ion?

Accepted Answer

Ignore the charge of the ion when counting electrons.

Chemical Bonding: Lewis Structures, Molecular Geometry, and Electronegativity

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