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Question (21)

QN0035892

A base dissolves in water and produces 0.20 mol OH- ions. Another produces 0.05 mol OH- ions under comparable conditions. Which solution is expected to show stronger basic character?

(A) The first solution
(B) The second solution
(C) Both equally
(D) Neither

Correct Answer: A

Explanation:

Greater production of OH- ions corresponds to greater basic strength.

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Question (22)

QN0035893

Which equation correctly represents the ionisation of Mg(OH)2 in water?

(A) Mg(OH)2 → Mg+ + OH-
(B) Mg(OH)2 → Mg2+ + 2OH-
(C) Mg(OH)2 → Mg2- + 2OH+
(D) Mg(OH)2 → Mg + H2O

Correct Answer: B

Explanation:

Mg(OH)2 → Mg2+(aq) + 2OH-(aq).

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Question (23)

QN0035894

A concentrated acid is to be diluted safely. Which procedure is consistent with the chapter?

(A) Add water rapidly to acid
(B) Add acid slowly to water with constant stirring
(C) Mix acid and water without stirring
(D) Heat the acid before dilution

Correct Answer: B

Explanation:

Dilution is highly exothermic, so concentrated acid should be added slowly to water with constant stirring.

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Question (24)

QN0035895

A student adds water to concentrated acid instead of adding acid to water. Why can this be dangerous?

(A) No heat is produced
(B) Heat may cause the mixture to splash and can cause burns
(C) The acid immediately becomes a salt
(D) Water becomes a strong acid

Correct Answer: B

Explanation:

Heat generated during improper dilution may cause splashing and burns.

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Question (25)

QN0035896

A person's stomach produces excess acid during indigestion. Which substance mentioned in the chapter can help neutralise it?

(A) Magnesium hydroxide
(B) Hydrochloric acid
(C) Methanoic acid
(D) Sulphuric acid

Correct Answer: A

Explanation:

Magnesium hydroxide, or milk of magnesia, is a mild base used as an antacid.

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Question (26)

QN0035897

If the pH of the mouth falls below 5.5, which consequence is associated with the chapter?

(A) Tooth enamel becomes completely insoluble to all substances
(B) Tooth decay can begin
(C) Saliva becomes strongly alkaline
(D) No chemical change occurs

Correct Answer: B

Explanation:

Tooth decay starts when the pH of the mouth falls below 5.5.

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Question (27)

QN0035898

A farmer finds that the soil is too acidic for healthy plant growth. Which substance mentioned in the chapter could be used to treat such soil?

(A) Quick lime
(B) Hydrochloric acid
(C) Sulphuric acid
(D) Acetic acid

Correct Answer: A

Explanation:

Quick lime can be used to treat acidic soil.

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Question (28)

QN0035899

A bee sting leaves an acid that causes irritation. Which type of substance can provide relief according to the chapter?

(A) A mild base
(B) A strong acid
(C) Another acid
(D) Neutral water only

Correct Answer: A

Explanation:

A mild base such as baking soda is mentioned as a remedy for bee-sting irritation.

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Question (29)

QN0035900

Three salts are formed from: strong acid + strong base, strong acid + weak base, and strong base + weak acid. Their expected pH values are respectively:

(A) 7, less than 7, more than 7
(B) Less than 7, 7, more than 7
(C) More than 7, less than 7, 7
(D) 7, more than 7, less than 7

Correct Answer: A

Explanation:

Strong acid-strong base salts are neutral, strong acid-weak base salts are acidic, and strong base-weak acid salts are basic.

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Question (30)

QN0035901

NaCl and Na2SO4 are classified in the same salt family because they have the same:

(A) Negative radical
(B) Positive radical
(C) Acid only
(D) Physical state

Correct Answer: B

Explanation:

NaCl and Na2SO4 belong to the family of sodium salts because both contain Na+.

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Question (21)

A base dissolves in water and produces 0.20 mol OH- ions. Another produces 0.05 mol OH- ions under comparable conditions. Which solution is expected to show stronger basic character?

Explanation:

Link:

Question (22)

Which equation correctly represents the ionisation of Mg(OH)2 in water?

Explanation:

Link:

Question (23)

A concentrated acid is to be diluted safely. Which procedure is consistent with the chapter?

Explanation:

Link:

Question (24)

A student adds water to concentrated acid instead of adding acid to water. Why can this be dangerous?

Explanation:

Link:

Question (25)

A person's stomach produces excess acid during indigestion. Which substance mentioned in the chapter can help neutralise it?

Explanation:

Link:

Question (26)

If the pH of the mouth falls below 5.5, which consequence is associated with the chapter?

Explanation:

Link:

Question (27)

A farmer finds that the soil is too acidic for healthy plant growth. Which substance mentioned in the chapter could be used to treat such soil?

Explanation:

Link:

Question (28)

A bee sting leaves an acid that causes irritation. Which type of substance can provide relief according to the chapter?

Explanation:

Link:

Question (29)

Three salts are formed from: strong acid + strong base, strong acid + weak base, and strong base + weak acid. Their expected pH values are respectively:

Explanation:

Link:

Question (30)

NaCl and Na2SO4 are classified in the same salt family because they have the same:

Explanation:

Link:

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