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.

Therefore, the Correct Answer is D.

Q #1: When copper sulfate is made by reacting copper oxide with sulfuric acid, the acid is heated. Why?

A. To increase the rate of reaction

B. To decrease the rate of reaction

C. To prevent the formation of byproducts

D. To decrease the energy of activation

Answer Explanation

A) To increase the rate of reaction (Correct Answer): Heating the sulfuric acid increases the kinetic energy of the particles, leading to more frequent and energetic collisions between the reactant particles. This, in turn, increases the rate of reaction between copper oxide and sulfuric acid, facilitating the production of copper sulfate.

B) To decrease the rate of reaction: Heating typically increases the rate of reaction by providing more energy for particles to overcome the activation energy barrier. Decreasing the temperature would slow down the reaction, which is not the intended outcome in this scenario.

C) To prevent the formation of byproducts: While heating may influence the selectivity of reactions and the formation of byproducts in some cases, the primary purpose of heating sulfuric acid in this context is to increase the rate of reaction rather than to prevent the formation of byproducts.

D) To decrease the energy of activation: Heating increases the energy of particles, helping them overcome the energy barrier required for the reaction to occur. Therefore, heating sulfuric acid would increase the energy of activation rather than decrease it.
Q #2: 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.
Q #3: 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.

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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:

More Questions on TEAS 7 Science

Q #1: When copper sulfate is made by reacting copper oxide with sulfuric acid, the acid is heated. Why?

Answer Explanation

Q #2: What type of reaction occurs between sulfuric acid and ammonia?

Answer Explanation

Q #3: 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

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