$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$$

Question 1

Which of the following best describes a compound?

Accepted Answer

A substance consisting of two or more elements in a fixed ratio.

Question 2

Which element makes up the largest percentage of body mass in humans?

Accepted Answer

Oxygen

Question 3

What is the atomic number of an element?

Accepted Answer

The number of protons in the nucleus.

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have different numbers of neutrons but the same number of protons.

Question 5

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 6

What is the main difference between a polar and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds have unequal sharing of electrons due to differences in electronegativity.

Question 7

Which of the following best explains why sodium chloride (NaCl) forms an ionic bond?

Accepted Answer

Sodium donates an electron to chlorine, resulting in oppositely charged ions that attract each other.

Question 8

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

Accepted Answer

Iron

Question 9

A radioactive isotope is useful in medical imaging because:

Accepted Answer

It decays spontaneously, emitting particles that can be detected.

Question 10

Which equation correctly represents the chemical reaction for cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 ightarrow 6CO_2 + 6H_2O + 	ext{Energy}$$

Question 11

Which property of water is primarily due to hydrogen bonding?

Accepted Answer

Its high specific heat capacity.

Question 12

If an atom has an atomic number of 8 and a mass number of 16, how many neutrons does it have?

Accepted Answer

8

Question 13

Which of the following best describes a chemical equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 14

Which element is NOT one of the four most abundant elements in living organisms?

Accepted Answer

Sulfur

Question 15

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical behavior of an atom.

Question 16

A molecule of ammonia ($$NH_3) $$forms hydrogen bonds with water molecules. Which atom in ammonia is most likely to participate in hydrogen bonding?

Accepted Answer

Nitrogen

Question 17

Which of the following is a consequence of the molecular shape determined by chemical bonds?

Accepted Answer

Molecular shape determines biological function.

Question 18

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 19

Which of the following is true about chemical reactions in living systems?

Accepted Answer

Chemical reactions involve the making and breaking of chemical bonds.

Question 20

Which of the following is the correct formula for photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{Energy} ightarrow C_6H_{12}O_6$ + 6O_2$$

The Chemical Context of Life: Foundations for General Biology

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