Which one of the following must be added to dilute hydrochloric acid to produce hydrogen?

A. Iron

B. Iron sulfide

C. Copper chloride

D. Sulfur

Answer Explanation:

A. Iron (Correct Answer): Iron can react with hydrochloric acid to produce hydrogen gas according to the following reaction:

2HCl + Fe => FeCl2 + H2

So, adding iron to dilute hydrochloric acid would produce hydrogen gas.

B. Iron sulfide: Iron sulfide may react with hydrochloric acid, but it does not directly produce hydrogen gas. The reaction would likely produce hydrogen sulfide gas instead.

C. Copper chloride: Copper chloride does not react with hydrochloric acid to produce hydrogen gas. The reaction between copper chloride and hydrochloric acid would likely produce copper chloride and hydrogen chloride gas.

D. Sulfur: Sulfur does not react with hydrochloric acid to produce hydrogen gas. The reaction between sulfur and hydrochloric acid would likely produce hydrogen sulfide gas.

Therefore, the Correct Answer is A.

Q #1: Why is KOH a strong alkali?

A. Because it reacts vigorously with acids

B. Because it forms a basic solution when dissolved in water

C. Because in solution it fully dissociates into K+ and OH-

D. Because it forms insoluble precipitates with metal cations

Answer Explanation

A) Because it reacts vigorously with acids: While KOH does react with acids to form salts and water, the strength of an alkali is not solely determined by its reactivity with acids.

B) Because it forms a basic solution when dissolved in water: This statement is true, but it does not fully explain why KOH is considered a strong alkali. Many compounds can form basic solutions when dissolved in water.

C) Because in solution it fully dissociates into K+ and OH- (Correct Answer): KOH is considered a strong alkali because it fully dissociates in aqueous solution into potassium ions (K+) and hydroxide ions (OH-). This dissociation leads to a high concentration of hydroxide ions in solution, making it strongly alkaline.

D) Because it forms insoluble precipitates with metal cations: This statement describes the formation of insoluble hydroxide precipitates when alkali solutions are added to solutions of metal salts. However, it does not fully explain why KOH itself is considered a strong alkali.
Q #2: Why is dry hydrogen chloride gas not acidic?

A. Because it does not react with water

B. Because it does not contain hydrogen ions (H+)

C. Because it contains hydrogen ions but not chloride ions (Cl-)

D. Because hydrogen is bonded to chlorine in dry HCl and not dissociated

Answer Explanation

A) Because it does not react with water: While dry hydrogen chloride gas does not react with water, the absence of this reaction does not inherently determine its acidity. Acidity is determined by the presence of hydrogen ions in solution.

B) Because it does not contain hydrogen ions (H+): Dry hydrogen chloride gas does not contain free hydrogen ions, which are characteristic of acidic solutions. However, the absence of hydrogen ions alone does not explain why dry hydrogen chloride gas is not acidic.

C) Because it contains hydrogen ions but not chloride ions (Cl-): Dry hydrogen chloride gas does not contain free chloride ions, but the presence of hydrogen ions is crucial for acidity. However, the absence of chloride ions alone does not fully explain why dry hydrogen chloride gas is not acidic.

D) Because hydrogen is bonded to chlorine in dry HCl and not dissociated (Correct Answer): Dry hydrogen chloride gas does not dissociate into hydrogen ions (H+) and chloride ions (Cl-) because there is no water present to facilitate dissociation. Therefore, it does not exhibit acidic properties in the absence of dissociation.
Q #3: Why do farmers use ammonium salts on their fields?

A. To prevent soil erosion

B. To increase soil acidity

C. To help plants grow (as fertilizers)

D. To reduce soil salinity

Answer Explanation

A) To prevent soil erosion: While certain soil management practices may involve measures to prevent erosion, the use of ammonium salts specifically does not directly relate to preventing soil erosion.

B) To increase soil acidity: Ammonium salts, such as ammonium sulfate, can actually decrease soil pH, making the soil more acidic. However, this is not typically the primary reason farmers use these salts.

C) To help plants grow (as fertilizers) (Correct Answer): Ammonium salts are commonly used as fertilizers because they provide essential nitrogen to plants in a form that they can readily absorb. Nitrogen is a crucial nutrient for plant growth, and ammonium salts serve as a source of nitrogen for crops.

D) To reduce soil salinity: Ammonium salts are not typically used to reduce soil salinity. Salinity issues in soil are typically addressed through other methods such as leaching or soil amendments, rather than the addition of ammonium salts.

Free Access on TEAS 7 Exams and Study Notes

Access to all TEAS 7 Exams
Performance Tracking and Analysis
Well Documented and Explained Questions and Answers
2000+ Questions and Correct Answers: Answers Well Explained
Libary of Detailed StudyNotes
Topical Questions and Answers on Examinable topics

Join Now

Which one of the following must be added to dilute hydrochloric acid to produce hydrogen?

More Questions on TEAS 7 Science

Q #1: Why is KOH a strong alkali?

Answer Explanation

Q #2: Why is dry hydrogen chloride gas not acidic?

Answer Explanation

Q #3: Why do farmers use ammonium salts on their fields?

Answer Explanation

Free Access on TEAS 7 Exams and Study Notes

TEAS 7 Exams (Q&A)

TEAS 7 Study Notes

TEAS 7 Topical Tests

TEAS 7 Study Guides

Quick Links

Refer a Friend