Properties of acids and bases Knowledge-Based Practice

Questions

1. 1.

   Which of the following observations confirms that an unknown aqueous solution is acidic rather than basic?

   • A) The solution conducts an electric current.
   • B) The solution reacts with magnesium ribbon to produce hydrogen gas.
   • C) The solution turns phenolphthalein indicator bright pink.
   • D) The solution feels slippery when rubbed between the fingertips.
2. 2.

   An aqueous solution feels slippery to the touch, turns red litmus paper blue, and conducts an electric current. Which of the following substances could be the solute in this solution?

   • A) Potassium hydroxide ($\text{KOH}$)
   • B) Hydrochloric acid ($\text{HCl}$)
   • C) Glucose ($\text{C}_6\text{H}_{12}\text{O}_6$)
   • D) Sodium chloride ($\text{NaCl}$)
3. 3.

   A student adds an unknown aqueous solution to solid sodium hydrogen carbonate and observes vigorous bubbling due to the release of carbon dioxide gas. Which conclusion regarding the nature of the unknown solution is correct?

   • A) It is basic because bases react with carbonates to produce carbon dioxide gas.
   • B) It is acidic because acids react with hydrogen carbonates to produce carbon dioxide gas and water.
   • C) It is neutral because only neutral salt solutions react with hydrogen carbonates.
   • D) It is strongly basic because hydroxide ions cause the rapid decomposition of hydrogen carbonates into gas.
4. 4.

   Which of the following statements correctly describes a general property of aqueous acid solutions?

   • A) They turn red litmus paper blue.
   • B) They feel slippery when touched.
   • C) They react with active metals to release hydrogen gas.
   • D) They have a pH value greater than 7 at 25 °C.
5. 5.

   Which of the following statements correctly describes a characteristic property of aqueous bases?

   • A) They react with active metals to produce carbon dioxide gas.
   • B) They turn red litmus paper blue and feel slippery to the touch.
   • C) They possess a pH value strictly below 7 at standard room temperature.
   • D) They vigorously release hydrogen gas when mixed with calcium carbonate.

Answers and step-by-step solutions appear after you finish the test.