Q: A solution has a hydrogen ion concentration of $$1 \times 10$$^{-5}$$ M. What is its pH?

$$pH = -\log_{10}(1 \times 10$$^{-5}$$) = 5$$

Question 1

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

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds form a more open crystal structure in the solid state.

Question 2

Which property of water is primarily responsible for the movement of water from the roots to the leaves in plants?

Accepted Answer

Cohesion and adhesion, which allow water molecules to stick to each other and to the walls of plant vessels.

Question 3

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$pH = -\log_{10}(1 	imes 10$$^{-5}$$) = 5$$

Question 4

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the complete transfer of one or more electrons from one atom to another, resulting in oppositely charged ions.

Question 5

Which of the following molecules would be least likely to dissolve in water?

Accepted Answer

A nonpolar molecule such as oil.

Question 6

What is the main reason water has a high specific heat compared to other substances?

Accepted Answer

Many hydrogen bonds must be broken for water molecules to move faster, requiring more energy.

Question 7

Which of the following is true about isotopes of an element?

Accepted Answer

They have the same number of protons but different numbers of neutrons.

Question 8

Which of the following best explains why water is an excellent solvent for polar and ionic substances?

Accepted Answer

Water is polar and can form hydrogen bonds with other polar molecules and ions.

Question 9

Which of the following statements about electronegativity is correct?

Accepted Answer

Oxygen is more electronegative than nitrogen, carbon, or hydrogen.

Question 10

A buffer is important in biological systems because it:

Accepted Answer

Minimizes changes in pH when acids or bases are added.

Question 11

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally, resulting in partial charges on the atoms.

Question 12

Which of the following is a real-life example of surface tension caused by water’s cohesive properties?

Accepted Answer

A paperclip floating on the surface of water.

Question 13

Which of the following equations correctly represents the relationship between pH and hydrogen ion concentration?

Accepted Answer

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

Question 14

Which of the following best explains why sodium (Na) forms a cation and chlorine (Cl) forms an anion in table salt (NaCl)?

Accepted Answer

Sodium loses an electron to achieve a full valence shell, becoming positively charged, while chlorine gains an electron, becoming negatively charged.

Question 15

Which of the following is NOT a property of water that is important for life?

Accepted Answer

Water contracts as it freezes, becoming denser than liquid water.

Question 16

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule consists of two or more atoms held together by covalent bonds, while a compound consists of atoms of different elements.

Question 17

Which of the following best explains why water can dissolve table salt (NaCl)?

Accepted Answer

The partial positive charges on water’s hydrogen atoms attract Cl$$^-$$ ions, and the partial negative charge on oxygen attracts Na$$^+$$ ions, pulling the ions apart.

Question 18

Which of the following is a correct statement about the atomic structure of carbon?

Accepted Answer

Carbon has 6 protons, 6 neutrons (in its most common isotope), and 6 electrons.

Question 19

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak electrical attraction between a partially positive hydrogen atom and a partially negative atom (such as oxygen or nitrogen) in another molecule.

Water and Carbon: The Chemical Basis of Life (Chapter 2 Study Notes)

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