Q: A solution has a proton concentration of $$3.0 \times 10$$^{-5}$$ M. What is the pH of this solution?

$$pH = -\log(3.0 \times 10$$^{-5}$$) \approx 4.5$$

Question 1

Which of the following best explains why carbon is able to form four covalent bonds with other atoms?

Accepted Answer

Carbon has four unpaired electrons in its valence shell, allowing it to form four covalent bonds.

Question 2

A molecule of methane ($$CH_4) is $$formed when carbon bonds with four hydrogen atoms. What type of bonds are present between the carbon and hydrogen atoms in methane?

Accepted Answer

Nonpolar covalent bonds

Question 3

Which of the following statements about hydrogen bonds is correct?

Accepted Answer

Hydrogen bonds are noncovalent interactions that occur between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 4

Which of the following best describes why hydrocarbons are insoluble in water?

Accepted Answer

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

Question 5

A solution has a proton concentration of $$3.0 	imes 10$$^{-5}$$ M. What is the pH of this solution?

Accepted Answer

$$pH = -\log(3.0 	imes 10$$^{-5}$$) \approx 4.5$$

Question 6

If the pH of a solution changes from 6 to 4, what happens to the proton concentration?

Accepted Answer

It increases by a factor of 100.

Question 7

Which of the following molecules contains a double covalent bond?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 8

Which of the following best describes the interaction between two water molecules?

Accepted Answer

A hydrogen bond forms between the hydrogen atom of one water molecule and the oxygen atom of another.

Question 9

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

Accepted Answer

$$pH = -\log [H^+]$$

Question 10

A farmer adds lime (calcium carbonate) to soil to increase the pH from 4 to 6. By what factor does the proton concentration change?

Accepted Answer

It decreases by a factor of 100.

Question 11

Which of the following is true about ionic bonds?

Accepted Answer

They result from the transfer of electrons from one atom to another, creating oppositely charged ions.

Question 12

Which of the following substances has the highest concentration of protons ($$[H^+]$$)?

Accepted Answer

Lemon juice

Question 13

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

Accepted Answer

Oxygen is more electronegative than hydrogen, resulting in unequal sharing of electrons.

Question 14

A solution has a pH of 4.7. What is the proton concentration of this solution?

Accepted Answer

$$[H^+] = 10$$^{-4.7}$$ \ M$$

Question 15

Which of the following is a real-world consequence of acid rain with a proton concentration 10,000 times greater than pure water?

Accepted Answer

The acid rain can damage plant and marine life due to its low pH.

Question 16

Which of the following best describes the difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity, while nonpolar covalent bonds involve equal sharing.

Question 17

Which of the following is the most acidic substance?

Accepted Answer

Lemon juice

Question 18

Which of the following best explains why sodium chloride ($$NaCl) $$dissolves easily in water?

Accepted Answer

Water is polar and stabilizes the ions through electrostatic interactions.

Question 19

Which of the following best describes the relationship between acids, bases, and proton concentration in aqueous solutions?

Accepted Answer

Acids increase $$[H^+]$$ and bases decrease $$[H^+].$$

Question 20

Which of the following is true about the valence shell of an atom?

Accepted Answer

It is the outermost shell containing electrons and determines the atom's chemical reactivity.

Chemical Basis of Life: Atoms, Bonds, and Molecular Structure (chapter 2)

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