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Acids, bases and pH

Biology • Atoms, Water & Chemical Bonds • Knowledge-Based • 5 questions

Acids, bases and pH Knowledge-Based Download PDF

Biology · Chemistry of Life · Biology · Atoms, Water & Chemical Bonds

5 Biology practice questions on Acids, bases and pH. Questions that assess core concepts and understanding.

Questions

  1. 1.

    Which of the following statements correctly distinguishes a weak acid from a strong acid in an aqueous solution?

    • A) A weak acid releases hydroxide ions instead of hydrogen ions in solution.
    • B) A weak acid lowers the pH of an aqueous solution more drastically than an equimolar strong acid.
    • C) A weak acid dissociates only partially into hydrogen ions and its conjugate base, establishing a dynamic equilibrium.
    • D) A weak acid completely ionizes in water but does so at a significantly slower chemical reaction rate.
  2. 2.

    Which of the following statements correctly describes a chemically neutral aqueous solution at 25 °C?

    • A) A neutral solution contains neither free hydrogen ions nor hydroxide ions.
    • B) A neutral solution has a hydroxide ion concentration that exceeds its hydrogen ion concentration.
    • C) A neutral solution is characterized by the complete absence of water molecule dissociation.
    • D) A neutral solution possesses equal concentrations of hydrogen ions and hydroxide ions.
  3. 3.

    Which of the following best describes how a base alters the chemical balance of an aqueous solution?

    • A) It increases the concentration of free hydrogen ions by directly releasing protons into the solution.
    • B) It decreases the concentration of free hydrogen ions by directly accepting protons or releasing hydroxide ions.
    • C) It converts polar water molecules into nonpolar molecules to prevent hydrogen bonding.
    • D) It forces the solution to maintain an equal ratio of hydrogen ions to hydroxide ions regardless of concentration.
  4. 4.

    Which statement best explains how a biological buffer resists changes in pH when an acid is added to an aqueous solution?

    • A) It accepts excess hydrogen ions (H+H^+) from the solution.
    • B) It releases additional hydrogen ions (H+H^+) into the solution.
    • C) It permanently breaks down water molecules into hydroxide ions (OH−OH^-).
    • D) It converts the aqueous solvent into a nonpolar substance to block ionization.
  5. 5.

    If the pH of an aqueous solution decreases from 7 to 4, how does the concentration of hydrogen ions (H+H^+) change?

    • A) It decreases by a factor of 1,000.
    • B) It increases by a factor of 1,000.
    • C) It increases by a factor of 3.
    • D) It decreases by a factor of 3.