$$[H^+] = 1 \times 10$$^{-4}$$ \text{ M}$$

Question 1

Which of the following statements best explains why water has a high specific heat compared to other substances?

Accepted Answer

Hydrogen bonds between water molecules absorb a significant amount of energy before breaking, resulting in a high specific heat.

Question 2

An atom of carbon has 6 protons, 6 neutrons, and 6 electrons. What is its atomic number and atomic weight?

Accepted Answer

Atomic number: 6, Atomic weight: 12

Question 3

Which type of chemical bond is formed by the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 4

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

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ 	ext{ M}$$

Question 5

Which property of water allows insects to walk on its surface?

Accepted Answer

Surface tension

Question 6

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

Accepted Answer

Polar covalent bonds share electrons unequally, resulting in partial charges; nonpolar covalent bonds share electrons equally.

Question 7

Which of the following best describes a buffer in a biological system?

Accepted Answer

A buffer is a combination of H+ donor and H+ acceptor that prevents large changes in pH.

Question 8

If a molecule is hydrophobic, what will happen when it is placed in water?

Accepted Answer

It will clump together with other hydrophobic molecules due to hydrophobic interaction.

Question 9

Which of the following is true about isotopes?

Accepted Answer

Isotopes are atoms of the same element with different numbers of neutrons.

Question 10

A sodium atom (Na) has one electron in its outer shell. What is most likely to happen during a chemical reaction?

Accepted Answer

It will lose its outer electron to form a positively charged ion (cation).

Question 11

Which of the following best describes the relationship between molecules and compounds?

Accepted Answer

A molecule is two or more atoms held together by chemical bonds; a compound is a molecule composed of two or more different elements.

Question 12

Which of the following equations correctly represents the dissociation of water?

Accepted Answer

$$H_2O \rightleftharpoons H^+ + OH^-$$

Question 13

A solution has a molarity of $$2 	ext{ M}$$ and contains $$1 	ext{ L} of $$solution. How many moles of solute are present?

Accepted Answer

$$2 	ext{ moles}$$

Question 14

Which of the following is a consequence of water expanding when it freezes?

Accepted Answer

Ice floats on water, insulating the liquid water below and helping aquatic life survive in cold climates.

Question 15

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the attraction between oppositely charged ions after electron transfer.

Question 16

Which property of water is most important for moderating Earth's climate?

Accepted Answer

High specific heat

Question 17

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

Accepted Answer

Double covalent bond

Question 18

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

Accepted Answer

An acid increases the concentration of $$H^+$$ ions in solution.

Question 19

Which of the following best explains why polar molecules are hydrophilic?

Accepted Answer

They have charged regions that interact favorably with water molecules.

Atoms, Molecules, and Life: Foundations of Chemistry in Biology

Guida di studio - Domande di pratica