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Question (11)

QN002721

A pure substance consists of particles that

(A) behave differently
(B) vary in composition
(C) behave identically
(D) are always visible

Correct Answer: C

Explanation:

All particles in a pure substance behave in the same way.

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Question (12)

QN002722

A student separates iron filings from sand using a magnet. This proves that the original sample was

(A) a pure substance
(B) an element
(C) a mixture
(D) a compound

Correct Answer: C

Explanation:

Mixtures can often be separated physically.

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Question (13)

QN002723

Which of the following cannot be classified as a pure substance?

(A) Carbon dioxide
(B) Iron
(C) Nitrogen
(D) Fruit juice

Correct Answer: D

Explanation:

Fruit juice contains many dissolved substances.

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Question (14)

QN002724

A substance contains only one kind of molecule throughout the sample. It is most likely

(A) a mixture
(B) a pure substance
(C) an alloy
(D) polluted air

Correct Answer: B

Explanation:

Pure substances contain only one type of particles.

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Question (15)

QN002725

Which process below indicates that a substance is NOT pure?

(A) It contains one type of particle
(B) It can be separated physically into components
(C) It behaves uniformly throughout
(D) It has fixed composition

Correct Answer: B

Explanation:

Physical separation indicates a mixture.

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Question (16)

QN002726

A shopkeeper mixes cheap oil with pure mustard oil to increase quantity. This practice is called

(A) condensation
(B) filtration
(C) adulteration
(D) distillation

Correct Answer: C

Explanation:

Adulteration involves adding inferior substances.

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Question (17)

QN002727

Which of the following is most suitable as an example of a pure substance in scientific terms?

(A) Seawater
(B) Lemonade
(C) Copper
(D) Muddy water

Correct Answer: C

Explanation:

Copper is an element and hence a pure substance.

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Question (18)

QN002728

A sample of water contains dissolved salt. The sample is

(A) a pure substance
(B) an element
(C) a mixture
(D) a compound only

Correct Answer: C

Explanation:

Salt dissolved in water forms a mixture.

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Question (19)

QN002729

According to science, which of the following pairs contains only pure substances?

(A) Air and milk
(B) Oxygen and iron
(C) Fruit juice and sugar syrup
(D) Soil and seawater

Correct Answer: B

Explanation:

Oxygen and iron each contain one kind of particles.

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Question (20)

QN002730

A chemist says that even products appearing clean and uniform may still be impure because they

(A) are always coloured
(B) contain dust particles
(C) may contain more than one substance
(D) dissolve in water

Correct Answer: C

Explanation:

Scientifically, presence of multiple substances means impurity.

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Question (11)

A pure substance consists of particles that

Explanation:

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Question (12)

A student separates iron filings from sand using a magnet. This proves that the original sample was

Explanation:

Link:

Question (13)

Which of the following cannot be classified as a pure substance?

Explanation:

Link:

Question (14)

A substance contains only one kind of molecule throughout the sample. It is most likely

Explanation:

Link:

Question (15)

Which process below indicates that a substance is NOT pure?

Explanation:

Link:

Question (16)

A shopkeeper mixes cheap oil with pure mustard oil to increase quantity. This practice is called

Explanation:

Link:

Question (17)

Which of the following is most suitable as an example of a pure substance in scientific terms?

Explanation:

Link:

Question (18)

A sample of water contains dissolved salt. The sample is

Explanation:

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Question (19)

According to science, which of the following pairs contains only pure substances?

Explanation:

Link:

Question (20)

A chemist says that even products appearing clean and uniform may still be impure because they

Explanation:

Link:

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