What color do acids make litmus paper turn?

A. Red

B. Yellow

C. Blue

D. Black

Answer Explanation:

A) Red (Correct Answer): Acids turn litmus paper red. Litmus paper is a common indicator that changes color in response to changes in acidity or alkalinity. Acids change the blue litmus paper to red.

B) Yellow: Acids do not typically turn litmus paper yellow. Litmus paper is generally unaffected by acids in a way that would cause it to turn yellow.

C) Blue: Acids do not turn litmus paper blue. Instead, they change blue litmus paper to red.

D) Black: Acids do not turn litmus paper black. Litmus paper is not expected to change to black in the presence of acids.

Therefore, the Correct Answer is A.

Q #1: Which acid is needed to make ammonium nitrate?

A. Sulfuric acid

B. Hydrochloric acid

C. Nitric acid

D. Acetic acid

Answer Explanation

A) Sulfuric acid: Sulfuric acid is not used in the production of ammonium nitrate. Although sulfuric acid is a widely used acid in various industries, it is not involved in the synthesis of ammonium nitrate.

B) Hydrochloric acid: Hydrochloric acid is not used in the production of ammonium nitrate. While it is an important industrial acid, it does not react with ammonia to produce ammonium nitrate.

C) Nitric acid (Correct Answer): Ammonium nitrate is typically produced by reacting ammonia (NH3) with nitric acid (HNO3). The reaction forms ammonium nitrate (NH4NO3), which is a common fertilizer and explosive compound.

D) Acetic acid: Acetic acid, commonly known as vinegar, is not used in the production of ammonium nitrate. It is a weak acid and does not react with ammonia to form ammonium nitrate.
Q #2: What is produced when an acid reacts with a metal hydroxide?

A. Salt and water

B. Carbon dioxide and water

C. Oxygen gas and water

D. Hydrogen gas and water

Answer Explanation

A) Salt and water (Correct Answer): When an acid reacts with a metal hydroxide, a salt and water are typically produced. The metal in the metal hydroxide combines with the acid to form a salt, and water is produced as a byproduct of the reaction.

B) Carbon dioxide and water: This reaction occurs when an acid reacts with a metal carbonate, not a metal hydroxide. When carbonates react with acids, carbon dioxide gas is produced along with water and a salt.

C) Oxygen gas and water: This reaction is not typical when an acid reacts with a metal hydroxide. Metal hydroxides generally do not produce oxygen gas when reacting with acids.

D) Hydrogen gas and water: This reaction occurs when an acid reacts with a metal, not a metal hydroxide. When metals react with acids, hydrogen gas is typically produced along with water and a salt.
Q #3: 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.

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What color do acids make litmus paper turn?

More Questions on TEAS 7 Science

Q #1: Which acid is needed to make ammonium nitrate?

Answer Explanation

Q #2: What is produced when an acid reacts with a metal hydroxide?

Answer Explanation

Q #3: Why is dry hydrogen chloride gas not acidic?

Answer Explanation

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