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: 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 #2: How can copper sulfate crystals be separated from copper sulfate solution?

A. Filtration

B. Distillation

C. Decantation

D. Evaporation

Answer Explanation

A) Filtration: Filtration is not suitable for separating dissolved substances from a solution. It is typically used to separate solid particles from a liquid mixture.

B) Distillation: Distillation is a process used to separate components of a mixture based on differences in their boiling points. It is not typically used to separate solid crystals from a solution.

C) Decantation: Decantation involves pouring off the liquid portion of a mixture, leaving the solid behind. While it can be used to separate solid and liquid phases, it may not effectively separate dissolved copper sulfate from the solution.

D) Evaporation (Correct Answer): Evaporation involves heating the solution to allow the solvent (water) to vaporize, leaving behind the solute (copper sulfate) as solid crystals. This process is commonly used to obtain solid crystals from a solution.
Q #3: What is produced when an acid reacts with a metal carbonate or metal hydrogen carbonate?

A. Salt and water

B. Carbon dioxide and water

C. Oxygen gas and water

D. Salt and hydrogen gas

Answer Explanation

A) Salt and water: This reaction occurs when an acid reacts with a metal hydroxide or a metal oxide, not with a metal carbonate or metal hydrogen carbonate.

B) Carbon dioxide and water (Correct Answer): When an acid reacts with a metal carbonate or metal hydrogen carbonate, carbon dioxide gas is produced along with water and a salt. The carbonates decompose into carbon dioxide gas, water, and a salt when reacting with acids.

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

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

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

Answer Explanation

Q #2: How can copper sulfate crystals be separated from copper sulfate solution?

Answer Explanation

Q #3: What is produced when an acid reacts with a metal carbonate or metal hydrogen carbonate?

Answer Explanation

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