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:pH is a measure of how acidic or basic a substance is. The pH scale ranges from:

A. 0–7

B. 7–14

C. 0–14

D. 1–10

Answer Explanation:

A. 0–7: This range corresponds to acidic solutions on the pH scale. A pH value below 7 indicates acidity.

B. 7–14: This range corresponds to basic solutions on the pH scale. A pH value above 7 indicates alkalinity.

C. 0–14 (Correct Answer): The pH scale ranges from 0 to 14, covering the entire spectrum of acidity and alkalinity. A pH value of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate alkalinity.

D. 1–10: This range does not encompass the full range of the pH scale. The pH scale extends beyond 10 for alkaline solutions and below 1 for highly acidic solutions. Therefore, this choice is incorrect.

Therefore, the Correct Answer is C.

More Questions on TEAS 7 Science

  • Q #1: How can solid lead iodide be separated from solution?

    A. Filtration

    B. Distillation

    C. Decantation

    D. Chromatography

    Answer Explanation

    A) Filtration: Solid lead iodide can be separated from the solution using filtration. Filtration involves passing the mixture through a filter paper or porous material, allowing the solid particles to be retained while the liquid passes through.

    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 lead iodide from a solution.

    C) Decantation: Decantation involves carefully 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 be as effective as filtration for separating fine solid particles like lead iodide.

    D) Chromatography: Chromatography is a technique used to separate and analyze mixtures based on differences in the components' distribution between two phases: a stationary phase and a mobile phase. It is not typically used for separating solid lead iodide from a solution.

  • Q #2: 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.

  • Q #3: Why is ethanoic acid a weak acid?

    A. Because it reacts slowly with bases

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

    C. Because it only partially dissociates in solution

    D. Because it has a low pH value

    Answer Explanation

    Rationale for each choice:

    A) Because it reacts slowly with bases: The rate of reaction with bases does not determine whether an acid is weak or strong. Ethanoic acid's reaction rate with bases is not a primary factor in its classification as a weak acid.

    B) Because it forms a basic solution when dissolved in water: This statement is incorrect. Ethanoic acid is an acid and forms acidic solutions when dissolved in water.

    C) Because it only partially dissociates in solution (Correct Answer): Ethanoic acid is considered a weak acid because it only partially dissociates into hydrogen ions (H+) and acetate ions (CH3COO-) in solution. This partial dissociation results in a lower concentration of hydrogen ions compared to strong acids.

    D) Because it has a low pH value: While weak acids generally have higher pH values compared to strong acids, the pH value alone does not determine whether an acid is weak or strong. Ethanoic acid's weak acidity is primarily attributed to its partial dissociation in solution, rather than its pH value.