Chemistry 9th Chap 5 : Topic 10 - Maryam Publications

Chemistry Chapter 5 : Topic 10

Ionization in Water

1 / 18

A student prepares four different aqueous solutions: hydrochloric acid (HCl), sugar solution, sodium chloride solution, and distilled water. When tested using a conductivity apparatus, only some solutions allow current to pass. Which explanation best justifies this behavior?

A) Sugar solution conducts electricity because it contains dissolved particles

B) Distilled water conducts more current due to purity

C) All solutions conduct electricity because water is always a good conductor

D) Only solutions that produce ions in water allow electric current to pass

2 / 18

When hydrochloric acid gas is dissolved in water, the resulting solution conducts electricity strongly. This happens because:

A) Water molecules become charged during dissolution

B) Acid changes into metal ions in solution

C) HCl ionizes into hydrogen ions and chloride ions in water

D) HCl molecules remain unchanged and move freely

3 / 18

A beaker contains pure ethanol, while another contains aqueous acetic acid. Only one conducts electricity weakly. What is the best explanation?

A) Acetic acid partially ionizes in water producing some ions

B) Ethanol produces more ions than acetic acid

C) Ethanol is ionic in nature

D) Both solutions fully ionize equally

4 / 18

Which statement correctly describes why solid sodium chloride does not conduct electricity but its aqueous solution does?

A) NaCl becomes covalent in solid form

B) Solid NaCl contains free electrons

C) NaCl breaks into atoms in solid state

D) Ions are free to move only when dissolved in water

5 / 18

A bulb glows brightly when dipped in hydrochloric acid solution but does not glow in sugar solution. What conclusion is correct?

A) HCl produces mobile ions, sugar does not ionize.

B) HCl is non-electrolyte.

C) Sugar contains metallic ions.

D) Sugar ionizes more than HCl.

6 / 18

Which process best explains how acids conduct electricity in aqueous solutions?

A) Dissolution into neutral molecules

B) Ionization into charged particles

C) Melting into liquid form

D) Evaporation into gas ions

7 / 18

A solution contains only water and dissolved glucose. Why does it not conduct electricity?

A) Glucose does not ionize into charged particles

B) Water destroys glucose molecules

C) Glucose completely evaporates in water

D) Glucose forms metallic bonds in water

8 / 18

Which statement best describes an electrolyte?

A) A substance that prevents conduction of electricity

B) A substance that only exists in solid form

C) A substance that produces ions when dissolved in water

D) A substance that dissolves but does not ionize in water

9 / 18

When sulfuric acid (H₂SO₄) is dissolved in water, it produces ions that conduct electricity. Which observation is expected?

A) Only neutral molecules are present

B) No change in electrical conductivity

C) High conductivity due to many ions

D) No ions are formed in solution

10 / 18

Why does distilled water conduct electricity very poorly?

A) It contains no molecules

B) It lacks free ions

C) It is a solid substance

D) It contains excess electrons

11 / 18

A student compares HCl and CH₃COOH solutions of equal concentration. HCl conducts better electricity. The correct reason is:

A) CH₃COOH produces more ions

B) CH₃COOH is a metal acid

C) HCl completely ionizes in water

D) HCl is more volatile

12 / 18

Which of the following will NOT conduct electricity in aqueous solution?

A) NaCl

B) H₂SO₄

C) Glucose

D) HCl

13 / 18

What is the main reason that ionic compounds conduct electricity in molten or aqueous state but not in solid state?

A) Ions become free to move

B) They become gases

C) Electrons are destroyed

D) They turn into atoms

14 / 18

Which statement best explains ionization of acids in water?

A) Acids form ions that move freely in solution

B) Acids break into neutral particles

C) Acids lose mass in water

D) Acids become metals in water

15 / 18

A solution shows weak electrical conductivity. What can be inferred?

A) It contains no solute

B) It contains partially ionizing substance

C) It contains only metals

D) It is completely non-polar

16 / 18

Which pair of substances will show highest difference in conductivity?

A) NaCl and H₂SO₄

B) HCl and sugar

C) Sugar and glucose

D) HCl and NaCl

17 / 18

What is the role of water in ionization of acids?

A) It destroys acid molecules

B) It converts acids into solids

C) It prevents dissociation

D) It acts as a medium for ion formation

18 / 18

Which of the following best describes the reason behind glowing of a bulb in acid solution?

A) Movement of neutral molecules

B) Movement of ions carrying charge

C) Heating effect of acid

D) Flow of electrons through solution

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