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: A universal indicator has the ability to indicate the full range of pH values on the pH scale by color changes. Acids change the color of universal indicator towards:

A. Yellow, green, and blue colors.

B. Green, blue, and purple colors.

C. White, grey, and black colors.

D. Yellow, orange, and red colors

Answer Explanation

A. Yellow, green, and blue colors: This sequence of colors does not represent the typical color changes observed in universal indicator when exposed to acidic solutions. Universal indicator typically changes from green/blue in neutral solutions to yellow/orange/red in acidic solutions.

B. Green, blue, and purple colors: Purple is not typically observed in the color changes of universal indicator in acidic solutions. Universal indicator usually transitions from green/blue in neutral solutions to yellow/orange/red in acidic solutions.

C. White, grey, and black colors: These colors are not typically observed in the color changes of universal indicator. Universal indicator undergoes a series of color changes from green/blue to yellow/orange/red in acidic solutions.

D. Yellow, orange, and red colors. (Correct Answer): Universal indicator typically changes from green/blue in neutral solutions to yellow/orange/red in acidic solutions. This sequence of colors represents the typical color changes observed in universal indicator when exposed to acidic solutions.
Q #2: What is produced when an acid reacts with a metal?

A. Salt and water

B. Carbon dioxide and water

C. Oxygen gas and water

D. Salt and hydrogen

Answer Explanation

A) Salt and water: This reaction occurs when an acid reacts with a metal hydroxide or a metal oxide. When metals react with acids, hydrogen gas is typically produced along with a salt, not water.

B) Carbon dioxide and water: This reaction occurs when an acid reacts with a metal carbonate, not a metal. 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. Metal reactions with acids usually produce hydrogen gas along with a salt.

D) Salt and hydrogen (Correct Answer): When an acid reacts with a metal, hydrogen gas is produced along with a salt. The metal displaces hydrogen ions from the acid, forming a salt, while hydrogen gas is released as a byproduct of the reaction.
Q #3: What type of reaction occurs between sulfuric acid and ammonia?

A. Oxidation

B. Reduction

C. Neutralization

D. Precipitation

Answer Explanation

A) Oxidation: Sulfuric acid and ammonia do not participate in an oxidation-reduction reaction, where one substance loses electrons (oxidation) and another gains electrons (reduction).

B) Reduction: Sulfuric acid and ammonia do not participate in an oxidation-reduction reaction, so reduction is not the correct type of reaction.

C) Neutralization (Correct Answer): When sulfuric acid reacts with ammonia, a neutralization reaction occurs. The acidic hydrogen ions (H+) from sulfuric acid react with the basic ammonia molecules (NH3) to form ammonium ions (NH4+) and sulfate ions (SO4^2-), resulting in the formation of an ammonium sulfate salt.

D) Precipitation: A precipitation reaction occurs when two solutions react to form an insoluble solid (precipitate). However, sulfuric acid and ammonia do not form an insoluble product when they react. Therefore, precipitation is not the correct type of reaction for this scenario.

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

More Questions on TEAS 7 Science

Q #1: A universal indicator has the ability to indicate the full range of pH values on the pH scale by color changes. Acids change the color of universal indicator towards:

Answer Explanation

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

Answer Explanation

Q #3: What type of reaction occurs between sulfuric acid and ammonia?

Answer Explanation

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