Question 1

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

Accepted Answer

The oxygen atom in water is more electronegative than the hydrogen atoms, resulting in an uneven distribution of charge.

Question 2

A radioactive isotope of carbon, $$^{14}C$$, is used in medical imaging. What makes $$^{14}C$$ different from the most common isotope, $$^{12}C$$?

Accepted Answer

$$^{14}C$$ has more neutrons than $$^{12}C.$$

Question 3

Which property of water allows a spider to walk on the surface of a pond without sinking?

Accepted Answer

Cohesion due to hydrogen bonding

Question 4

Which of the following best describes the difference between a covalent bond and an ionic bond?

Accepted Answer

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Question 5

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 10$$^{-4}$$ M

Question 6

Which of the following is a real-life example of a buffer system in the human body?

Accepted Answer

The bicarbonate buffer system in blood

Question 7

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

Accepted Answer

Hydrogen bonds keep water molecules in ice farther apart, making ice less dense.

Question 8

Which of the following functional groups acts as an acid by donating a hydrogen ion ($$H^+$$)?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 9

How many times more acidic is a solution with pH 2 compared to a solution with pH 5?

Accepted Answer

1,000 times

Question 10

Which of the following statements about carbon is FALSE?

Accepted Answer

Carbon is the most abundant element in the human body.

Question 11

Which of the following best describes the role of electronegativity in the formation of polar covalent bonds?

Accepted Answer

Polar covalent bonds form when one atom is significantly more electronegative than the other, causing unequal sharing of electrons.

Question 12

Which of the following is an example of a chemical reaction?

Accepted Answer

Burning methane: $$CH_4 + 2$$ $$O_2$$ \rightarrow $$CO_2 + 2 H_2O$

Question 13

Which property of water is most responsible for the moderation of coastal climates?

Accepted Answer

High specific heat

Question 14

Which of the following best describes the difference between structural isomers and enantiomers?

Accepted Answer

Structural isomers differ in covalent arrangements; enantiomers are mirror images of each other.

Question 15

A molecule with the formula $$C_3H_8 is $$best described as a:

Accepted Answer

Hydrocarbon

Question 16

Which of the following best explains why oil does not dissolve in water?

Accepted Answer

Oil molecules are nonpolar and cannot form hydrogen bonds with water.

Question 17

Which of the following is the correct formula for calculating the pH of a solution?

Accepted Answer

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

Question 18

Which of the following best describes the role of ATP in cells?

Accepted Answer

ATP stores and releases energy for cellular processes.

Question 19

Which of the following statements about hydrogen bonds is TRUE?

Accepted Answer

Hydrogen bonds form between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 20

A solution is made by dissolving 18 grams of glucose ($$C_6H_{12}O_6$; molecular mass = 180 g/mol) in enough water to make 1 liter of solution. What is the molarity (M) of the solution?

Accepted Answer

0.1 M

The Chemical Context of Life, Water, and Carbon: Foundations for General Biology

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