Question 1

Which of the following best explains why the soil in El Yunque National Forest, as shown in the image, is very red and acidic?

Accepted Answer

The high rainfall leads to leaching of basic minerals, leaving behind iron oxides that give the soil a red color and increase acidity.

Question 2

According to the Arrhenius theory, which of the following substances is classified as a base?

Accepted Answer

NaOH, because it produces $$OH^-$$ ions in aqueous solution.

Question 3

Which of the following equations correctly represents the neutralization reaction between nitric acid and potassium hydroxide?

Accepted Answer

$$HNO_3 + $$KOH \rightarrow $$KNO_3 + H_2O$

Question 4

A farmer is shown spreading lime on a field. What is the primary chemical purpose of this agricultural practice?

Accepted Answer

To neutralize acidic soils by increasing the pH through the addition of a base.

Question 5

Which of the following substances will be the least soluble in water, based on their polarity?

Accepted Answer

C$$_6H$_6 ($$benzene), because it is nonpolar and water is polar.

Question 6

Which of the following will exhibit hydrogen bonding?

Accepted Answer

H$$_2O$$, because hydrogen is bonded directly to oxygen.

Question 7

Which of the following best describes a salt formed from a neutralization reaction?

Accepted Answer

An ionic compound composed of cations other than hydrogen and anions other than hydroxide.

Question 8

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

Accepted Answer

$$pH = 5$$

Question 9

Which of the following statements about strong and weak acids is correct?

Accepted Answer

Strong acids ionize completely in water, while weak acids ionize only partially.

Question 10

Which of the following is a limitation of the Arrhenius theory of acids and bases?

Accepted Answer

It does not explain the basicity of ammonia and similar compounds.

Question 11

According to the Brønsted-Lowry theory, which of the following is a base?

Accepted Answer

NH$$_3$$, because it accepts a proton from water.

Question 12

A laboratory titration is performed to determine the concentration of an unknown acid. Which of the following best describes the process?

Accepted Answer

A base of known concentration is added to the acid until neutralization is achieved, allowing calculation of the acid's concentration.

Question 13

Which of the following best explains why ocean acidification is a concern for marine life?

Accepted Answer

Lower pH reduces carbonate ion availability, making it harder for organisms to form shells and skeletons.

Question 14

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

Accepted Answer

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

Question 15

Which of the following is a real-world example of a neutralization reaction?

Accepted Answer

Using vinegar (acetic acid) to neutralize a lye (sodium hydroxide) spill on a countertop.

Question 16

Which of the following best describes an electrolyte?

Accepted Answer

A salt that conducts electricity when dissolved in water.

Question 17

Which of the following best explains why ammonia (NH$$_3) is $$considered a base under the Brønsted-Lowry theory but not under the Arrhenius theory?

Accepted Answer

Ammonia accepts a proton from water, forming $$NH_4$$^+$$ and OH$$^-$$, but does not produce OH$$^-$$ directly in water.

Question 18

Which of the following solutions would have the highest electrical conductivity?

Accepted Answer

A solution of NaCl, because it dissociates completely into ions.

Question 19

Which of the following best describes the effect of increased CO$$_2$$ respiration by roots and microbes near the soil surface?

Accepted Answer

It lowers the soil pH near the surface due to increased carbonic acid formation.

Lecture 17

Guida di studio - Domande di pratica