Question 1

Which statement best describes the difference between an atom and a molecule?

Accepted Answer

An atom is the smallest unit of matter, while a molecule is a structure formed by two or more atoms joined by chemical bonds.

Question 2

Which of the following best explains why isotopes of the same element have different atomic weights?

Accepted Answer

They have different numbers of neutrons.

Question 3

A neutral atom of carbon-14 has how many protons, neutrons, and electrons?

Accepted Answer

6 protons, 8 neutrons, 6 electrons

Question 4

Which equation correctly represents the relationship between atomic number ($$Z$$), number of protons ($$p$$), and number of electrons ($$e) in a $$neutral atom?

Accepted Answer

$$Z = p = e$$

Question 5

According to the Bohr model (as shown in the first image), what happens when an electron absorbs a quantum of energy ($$h
u$$)?

Accepted Answer

The electron moves to a higher energy level.

Question 6

Which property of water is primarily responsible for its high surface tension?

Accepted Answer

Cohesion between water molecules due to hydrogen bonding.

Question 7

What is the molar mass of water ($$H_2O$$)?

Accepted Answer

$$18\ \mathrm{g/mol}$$

Question 8

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Question 9

A solution is prepared by dissolving 58.5 g of NaCl (molar mass = $$58.5\ \mathrm{g/mol}) in $$enough water to make 1.0 L of solution. What is the molarity ($$M) of $$the solution?

Accepted Answer

$$1.0\ M$$

Question 10

Which formula correctly relates pH and hydrogen ion concentration $$[H^+]$$?

Accepted Answer

$$\mathrm{pH} = -\log_{10}[H^+]$$

Question 11

If the pH of a solution decreases from 7 to 5, what happens to the hydrogen ion concentration?

Accepted Answer

It increases by 100 times.

Question 12

Which of the following best describes a hydration shell?

Accepted Answer

A layer of water molecules surrounding a dissolved ion.

Question 13

Which of the following is a property of noble gases such as helium, neon, and argon?

Accepted Answer

They have full outer energy levels and are chemically unreactive.

Question 14

Which functional group is present in all alcohols?

Accepted Answer

Hydroxyl group ($$-OH)$$

Question 15

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

Question 16

What is the product when ammonia ($$NH_3) $$reacts with water?

Accepted Answer

$$NH_4$$^+$$ (ammonium ion) \ 	ext{and} \ OH^- (hydroxide ion)$

Question 17

Which of the following best describes the geometry of a methane ($$CH_4) $$molecule?

Accepted Answer

Tetrahedral

Question 18

Which of the following is true about the specific heat of water?

Accepted Answer

Water has a high specific heat, allowing it to moderate Earth's climate.

Question 19

Which of the following is the correct formula for calculating the molecular weight of a compound?

Accepted Answer

$$	ext{Molecular weight} = \sum 	ext{(atomic weights of all atoms in the molecule)}$$

Atomic Structure, Chemical Bonds, and Water: Foundations of Biological Chemistry

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