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Question (41)

QN0036012

A solution contains 5–8% acetic acid in water and is commonly used as a preservative in pickles. What is this solution called?

(A) Alcohol
(B) Vinegar
(C) Methanol
(D) Ester

Correct Answer: B

Explanation:

A 5–8% solution of

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Question (42)

QN0036013

Ethanoic acid and ethanol are heated together in the presence of an acid catalyst. A sweet-smelling compound is produced. What type of compound is it?

(A) Ester
(B) Alkane
(C) Soap
(D) Detergent

Correct Answer: A

Explanation:

Ethanoic acid reacts with ethanol in the presence of an acid catalyst to form an ester, which generally has a sweet smell.

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Question (43)

QN0036014

An ester is treated with sodium hydroxide and gives an alcohol and a sodium salt of a carboxylic acid. What is this reaction called?

(A) Hydrogenation
(B) Saponification
(C) Substitution
(D) Combustion

Correct Answer: B

Explanation:

The alkaline hydrolysis of an ester to form alcohol and the sodium salt of a carboxylic acid is called saponification.

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Question (44)

QN0036015

A soap molecule is placed at the boundary between oil and water. Which arrangement is most suitable for its cleaning action?

(A) Ionic end toward oil and hydrocarbon tail toward water
(B) Both ends toward water
(C) Ionic end toward water and hydrocarbon tail toward oil
(D) Both ends toward oil

Correct Answer: C

Explanation:

The ionic/hydrophilic end interacts with water while the hydrocarbon/hydrophobic end interacts with oily dirt.

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Question (45)

QN0036016

A micelle contains oily dirt at its centre. Which orientation of soap molecules makes this possible?

(A) Hydrophobic tails inside and ionic ends outside
(B) Ionic ends inside and hydrophobic tails outside
(C) Both ends inside
(D) Both ends outside

Correct Answer: A

Explanation:

In a micelle, hydrophobic tails point inward toward the oily dirt, while ionic ends face the surrounding water.

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Question (46)

QN0036017

A student adds soap to hard water and observes a white curdy precipitate. Which ions are mainly responsible for this problem?

(A) Na⁺ and K⁺
(B) Ca²⁺ and Mg²⁺
(C) H⁺ and Cl⁻
(D) O²⁻ and H⁺

Correct Answer: B

Explanation:

Calcium and magnesium salts responsible for hardness react with soap and form insoluble scum.

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Question (47)

QN0036018

Equal quantities of soap are added separately to soft water and hard water. Which result is expected?

(A) Hard water generally produces more foam.
(B) Soft water generally produces more foam.
(C) Both always produce exactly the same foam.
(D) Neither produces foam.

Correct Answer: B

Explanation:

Calcium and magnesium ions in hard water react with soap and form scum, reducing its cleansing effectiveness and foam formation.

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Question (48)

QN0036019

A detergent is added to hard water instead of soap. Why does the detergent remain effective?

(A) It contains no carbon.
(B) Its charged ends do not form insoluble precipitates with calcium and magnesium ions.
(C) It converts hard water into distilled water.
(D) It removes all calcium ions by evaporation.

Correct Answer: B

Explanation:

Detergents remain effective in hard water because their charged ends do not form insoluble precipitates with Ca²⁺ and Mg²⁺ ions.

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Question (49)

QN0036020

A student compares the chemical behaviour of CH₃OH, C₂H₅OH, C₃H₇OH and C₄H₉OH. Why are their chemical properties expected to be similar?

(A) They have exactly the same molecular mass.
(B) They contain the same functional group.
(C) They contain the same number of carbon atoms.
(D) They all have identical structures.

Correct Answer: B

Explanation:

These compounds belong to the same homologous series and contain the same alcohol functional group, which determines their characteristic chemical properties.

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Question (50)

QN0036021

A student has five hydrocarbons: C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄. Which pair is expected to undergo addition reactions?

(A) C₂H₆ and CH₄
(B) C₃H₈ and C₂H₆
(C) C₃H₆ and C₂H₂
(D) CH₄ and C₃H₈

Correct Answer: C

Explanation:

C₃H₆ contains a double bond and C₂H₂ contains a triple bond; unsaturated hydrocarbons undergo addition r

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Question (41)

A solution contains 5–8% acetic acid in water and is commonly used as a preservative in pickles. What is this solution called?

Explanation:

Link:

Question (42)

Ethanoic acid and ethanol are heated together in the presence of an acid catalyst. A sweet-smelling compound is produced. What type of compound is it?

Explanation:

Link:

Question (43)

An ester is treated with sodium hydroxide and gives an alcohol and a sodium salt of a carboxylic acid. What is this reaction called?

Explanation:

Link:

Question (44)

A soap molecule is placed at the boundary between oil and water. Which arrangement is most suitable for its cleaning action?

Explanation:

Link:

Question (45)

A micelle contains oily dirt at its centre. Which orientation of soap molecules makes this possible?

Explanation:

Link:

Question (46)

A student adds soap to hard water and observes a white curdy precipitate. Which ions are mainly responsible for this problem?

Explanation:

Link:

Question (47)

Equal quantities of soap are added separately to soft water and hard water. Which result is expected?

Explanation:

Link:

Question (48)

A detergent is added to hard water instead of soap. Why does the detergent remain effective?

Explanation:

Link:

Question (49)

A student compares the chemical behaviour of CH₃OH, C₂H₅OH, C₃H₇OH and C₄H₉OH. Why are their chemical properties expected to be similar?

Explanation:

Link:

Question (50)

A student has five hydrocarbons: C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄. Which pair is expected to undergo addition reactions?

Explanation:

Link:

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