$$2 \times 1.00794 + 15.9994 = 18.01528\ \text{g/mol}$$

Question 1

Which of the following best explains why water is considered an excellent temperature buffer in living organisms?

Accepted Answer

Water's high specific heat due to strong hydrogen bonding requires more energy to change its temperature.

Question 2

A sodium atom (Na) has 11 protons and 11 electrons. If it loses one electron to form a sodium ion (Na⁺), what is the resulting charge and why?

Accepted Answer

The sodium ion has a +1 charge because it has one more proton than electron.

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 4

Which of the following equations correctly represents a synthesis (anabolic) reaction?

Accepted Answer

$$A + B \rightarrow AB$$

Question 5

What is the molar mass of water ($$H_2O$$)? (Atomic masses: H = 1.00794 g/mol, O = 15.9994 g/mol)

Accepted Answer

$$2 	imes 1.00794 + 15.9994 = 18.01528\ 	ext{g/mol}$$

Question 6

Which of the following statements about acids and bases is correct?

Accepted Answer

Acids are proton ($$H^+) $$donors, while bases are proton acceptors that often release $$OH^-$$ ions.

Question 7

A chemical reaction in which energy is absorbed and the products have more energy than the reactants is called:

Accepted Answer

An endergonic reaction

Question 8

Which property of water allows it to dissolve ionic compounds like sodium chloride ($$NaCl$$)?

Accepted Answer

Its polarity, which allows water molecules to surround and separate ions.

Question 9

Which of the following best describes a decomposition (catabolic) reaction?

Accepted Answer

$$AB \rightarrow A + B$$

Question 10

Which of the following is NOT a characteristic of organic compounds?

Accepted Answer

They are always composed of carbon, hydrogen, and oxygen in a fixed 2:1:1 ratio.

Question 11

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Hydrogen bonding causes water molecules in ice to be arranged less densely than in liquid water.

Question 12

Which of the following is a correct example of an exchange reaction?

Accepted Answer

$$AB + CD \rightarrow AD + CB$$

Question 13

Which of the following statements about ATP (adenosine triphosphate) is correct?

Accepted Answer

ATP stores and releases energy for cellular processes by breaking and forming phosphate bonds.

Question 14

Which of the following best describes the role of functional groups in organic molecules?

Accepted Answer

They determine the chemical properties and reactivity of organic molecules.

Question 15

Which of the following is a property of water that is essential for life and is a direct result of its polarity?

Accepted Answer

It can act as a solvent for many ionic and polar substances.

Question 16

Which of the following best explains why carbon is the backbone of organic molecules?

Accepted Answer

Carbon can form four covalent bonds, allowing for complex and diverse molecular structures.

Question 17

A solution has a high concentration of $$H^+$$ ions. Which of the following best describes this solution?

Accepted Answer

It is acidic.

Question 18

Which of the following best describes a reversible chemical reaction?

Accepted Answer

$$A + B \rightleftharpoons AB$$

Question 19

Which of the following is a correct statement about macromolecules in living cells?

Accepted Answer

They are formed by dehydration synthesis, linking monomers into polymers.

Question 20

Which of the following best explains the importance of isotopes in microbiology?

Accepted Answer

Isotopes are used in biological research, medical diagnostics, and sterilization methods.

Chapter 2: Chemical Principles – Foundations of Microbial Chemistry

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