$$6 \times 12 + 12 \times 1 + 6 \times 16$$

Question 1

Which of the following best describes the difference between an atomic number and a mass number?

Accepted Answer

Atomic number is the number of protons in an atom, while mass number is the sum of protons and neutrons.

Question 2

Given an atom with atomic number $$Z = 8$$ and mass number $$A = 16$$, how many neutrons does it have?

Accepted Answer

$$8$$ neutrons

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same atomic number but different mass numbers.

Question 4

Which element is most likely to form ionic bonds with chlorine ($$Cl$$)?

Accepted Answer

Sodium ($$Na)$$

Question 5

A molecule of water ($$H_2O) is $$held together by which type of bond?

Accepted Answer

Covalent bonds

Question 6

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence electron shell, making them stable.

Question 7

Which of the following molecules is non-polar?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 8

If an atom has 11 protons, 12 neutrons, and 10 electrons, what is its charge?

Accepted Answer

$$+1$$

Question 9

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 10

Which formula represents the molecular weight of glucose ($$C_6H_{12}O_6$)? (Atomic weights: C = 12$, H = 1$, O = 16$)

Accepted Answer

$$6 	imes 12 + 12 	imes 1 + 6 	imes 16$$

Question 11

Which of the following is true about chemical reactions at equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 12

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on atoms.

Question 13

Which statement correctly describes the relationship between valence electrons and chemical reactivity?

Accepted Answer

Atoms with incomplete valence shells tend to react to achieve stability.

Question 14

Which of the following is a trace element essential for human health?

Accepted Answer

Iron

Question 15

Which of the following best distinguishes a molecule from a compound?

Accepted Answer

A molecule is a group of atoms bonded together, which can be of the same or different elements; a compound is a molecule made of different elements.

Question 16

Which of the following is the correct electron configuration for a neutral atom of carbon ($$Z = 6$$)?

Accepted Answer

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

Question 17

Which of the following is a correct example of a reversible chemical reaction?

Accepted Answer

$$CO_2 + H_2O$$ \rightleftharpoons H_2CO_3$$

Question 18

Which of the following best describes the Lewis dot method for representing atoms?

Accepted Answer

It shows the valence electrons as dots around the chemical symbol.

Question 19

Which of the following is NOT a van der Waals interaction?

Accepted Answer

Hydrogen bonding between water molecules.

Question 20

Which of the following best describes electronegativity?

Accepted Answer

The ability of an atom to attract electrons in a covalent bond.

The Chemical Context of Life: Atoms, Elements, and Chemical Bonds

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