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Question (1)

QN0028996

A jeweller adds 2 g of copper to 18 g of gold while making ornaments. The main purpose of adding copper is to

(A) decrease the melting point completely
(B) make gold ornaments harder and stronger
(C) convert gold into a compound
(D) remove impurities from gold

Correct Answer: B

Explanation:

Copper forms an alloy with gold, increasing hardness.

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Question (2)

QN0028997

A student mixes sand and iron filings. Which method will separate the two most effectively?

(A) Sedimentation
(B) Distillation
(C) Magnetism
(D) Evaporation

Correct Answer: C

Explanation:

Iron is magnetic while sand is non-magnetic.

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Question (3)

QN0028998

Which statement correctly distinguishes a compound from a mixture?

(A) Compounds have variable composition
(B) Mixtures are always pure substances
(C) Compounds are formed chemically in fixed ratio
(D) Mixtures cannot be separated physically

Correct Answer: C

Explanation:

Compounds are formed by chemical combination in fixed proportion.

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Question (4)

QN0028999

A student heats sugar strongly and notices black residue and water droplets. This activity proves that sugar

(A) is an element
(B) is a mixture only
(C) contains more than one element
(D) cannot decompose

Correct Answer: C

Explanation:

Sugar decomposes into carbon and water on heating.

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Question (5)

QN0029000

Which of the following is the best example of a pure substance?

(A) Air
(B) Soil
(C) Copper
(D) Lemon juice

Correct Answer: C

Explanation:

Copper contains only one type of particles.

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Question (6)

QN0029001

During electrolysis of water, one test tube collects nearly double the gas volume compared to the other. The gas collected in larger amount is

(A) oxygen
(B) nitrogen
(C) hydrogen
(D) carbon dioxide

Correct Answer: C

Explanation:

Water contains hydrogen and oxygen in 2:1 ratio.

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Question (7)

QN0029002

A mixture contains chalk powder, water, and small iron nails. Which sequence will separate all components correctly?

(A) Evaporation → Magnet
(B) Magnet → Filtration
(C) Filtration → Distillation
(D) Sedimentation → Condensation

Correct Answer: B

Explanation:

Magnet removes iron nails first; filtration separates chalk from water.

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Question (8)

QN0029003

Which property makes stainless steel suitable for making kitchen utensils?

(A) Low strength
(B) High reactivity
(C) Resistance to corrosion
(D) Poor heat conduction

Correct Answer: C

Explanation:

Stainless steel does not rust easily.

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Question (9)

QN0029004

Which mineral is most suitable for making electrical insulators?

(A) Graphite
(B) Mica
(C) Hematite
(D) Quartz

Correct Answer: B

Explanation:

Mica is a good electrical insulator.

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Question (10)

QN0029005

A student observes that iron sulfide formed after heating iron and sulfur is not attracted by a magnet. This is because

(A) sulfur destroys magnetic force
(B) iron evaporates completely
(C) a new compound with different properties is formed
(D) magnets attract only mixtures

Correct Answer: C

Explanation:

Compounds have properties different from constituent elements.

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Question (1)

A jeweller adds 2 g of copper to 18 g of gold while making ornaments. The main purpose of adding copper is to

Explanation:

Link:

Question (2)

A student mixes sand and iron filings. Which method will separate the two most effectively?

Explanation:

Link:

Question (3)

Which statement correctly distinguishes a compound from a mixture?

Explanation:

Link:

Question (4)

A student heats sugar strongly and notices black residue and water droplets. This activity proves that sugar

Explanation:

Link:

Question (5)

Which of the following is the best example of a pure substance?

Explanation:

Link:

Question (6)

During electrolysis of water, one test tube collects nearly double the gas volume compared to the other. The gas collected in larger amount is

Explanation:

Link:

Question (7)

A mixture contains chalk powder, water, and small iron nails. Which sequence will separate all components correctly?

Explanation:

Link:

Question (8)

Which property makes stainless steel suitable for making kitchen utensils?

Explanation:

Link:

Question (9)

Which mineral is most suitable for making electrical insulators?

Explanation:

Link:

Question (10)

A student observes that iron sulfide formed after heating iron and sulfur is not attracted by a magnet. This is because

Explanation:

Link:

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