Question 1

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

Accepted Answer

Oxygen attracts electrons more strongly than hydrogen, resulting in a partial negative charge on oxygen and a partial positive charge on hydrogen.

Question 2

A carbon atom has an atomic number of 6 and a mass number of 14. How many neutrons does it have?

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers maintain pH stability by converting strong acids or bases into weaker ones.

Question 4

Which chemical bond is the strongest and involves the sharing of electrons between atoms?

Accepted Answer

Covalent bond

Question 5

A sodium atom ($$Na) $$loses one electron to become a sodium ion ($$Na^+). $$What is the resulting charge and why?

Accepted Answer

Positive, because it has more protons than electrons.

Question 6

Which of the following elements is most abundant in the human body?

Accepted Answer

Oxygen ($$O)$$

Question 7

What is the correct chemical formula for glucose?

Accepted Answer

$$C_6H_{12}O_6$

Question 8

Which property of water allows trees to transport water from their roots to their leaves?

Accepted Answer

Cohesion due to hydrogen bonding

Question 9

If a solution has a pH of 2, which of the following statements is true?

Accepted Answer

The solution is acidic and has a high concentration of $$H^+$$ ions.

Question 10

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

Accepted Answer

Hydrogen bonds in ice create a lattice that spaces molecules farther apart, making ice less dense.

Question 11

Which of the following is a trace element required by humans in very small amounts?

Accepted Answer

Iron ($$Fe)$$

Question 12

A molecule contains a carboxyl group ($$-COOH). $$Which type of molecule is this most likely to be?

Accepted Answer

A protein or amino acid

Question 13

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the attraction between oppositely charged ions.

Question 14

Which of the following molecules is hydrophobic and will not dissolve in water?

Accepted Answer

Oil

Question 15

Which functional group is represented by $$-OH$$ and is commonly found in alcohols?

Accepted Answer

Hydroxyl group

Question 16

A radioactive isotope of carbon ($$^{14}C) is $$used in medical diagnostics. What property makes it useful for this purpose?

Accepted Answer

It emits radiation as its nucleus decays, which can be detected.

Question 17

Which of the following best describes the relationship between solute, solvent, and solution?

Accepted Answer

A solvent is the substance in which a solute is dissolved, forming a solution.

Question 18

Which of the following equations correctly represents the bicarbonate buffering system in blood?

Accepted Answer

$$H_2O + CO_2$ \leftrightarrow H_2CO_3 \leftrightarrow $$HCO_3$$^- + H^+$$

Question 19

Which of the following best explains why water has a high specific heat capacity?

Accepted Answer

Hydrogen bonds between water molecules require significant energy to break.

Question 20

A molecule of oxygen gas ($$O_2) is $$held together by which type of bond?

Accepted Answer

Double covalent bond

Essential Chemistry for Biology: Atoms, Elements, and Water

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