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Question 1:

Which concentration unit expresses the number of moles of solute per liter of solution?

A) Molarity (M)
B) Molality (m)
C) Mass percent (wt%)
D) Volume percent (vol%)

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Explanation: The correct answer is A) Molarity (M). Molarity is a concentration unit that expresses the number of moles of solute per liter of solution. It is commonly used in chemistry and represented by the symbol "M".

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Question 2:

Which concentration unit expresses the number of moles of solute per kilogram of solvent?

A) Molarity (M)
B) Molality (m)
C) Mass percent (wt%)
D) Volume percent (vol%)

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Explanation: The correct answer is B) Molality (m). Molality is a concentration unit that expresses the number of moles of solute per kilogram of solvent. It is particularly useful when temperature changes significantly, as it is independent of temperature and only depends on the mass of the solvent.

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Question 3:

Which concentration unit expresses the mass of solute as a percentage of the total mass of the solution?

A) Molarity (M)
B) Molality (m)
C) Mass percent (wt%)
D) Volume percent (vol%)

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Explanation: The correct answer is C) Mass percent (wt%). Mass percent is a concentration unit that expresses the mass of solute as a percentage of the total mass of the solution. It is often denoted as "wt%" or "% w/w".

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Question 4:

Which concentration unit expresses the volume of solute as a percentage of the total volume of the solution?

A) Molarity (M)
B) Molality (m)
C) Mass percent (wt%)
D) Volume percent (vol%)

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Explanation: The correct answer is D) Volume percent (vol%). Volume percent is a concentration unit that expresses the volume of solute as a percentage of the total volume of the solution. It is often denoted as "vol%" or "% v/v".

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Question 5:

Which concentration unit is preferred when dealing with reactions that involve gases or volatile substances?

A) Molarity (M)
B) Molality (m)
C) Mass percent (wt%)
D) Parts per million (ppm)

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Explanation: The correct answer is A) Molarity (M). Molarity is preferred when dealing with reactions that involve gases or volatile substances because it directly relates the number of moles of solute to the volume of the solution, allowing for precise measurements and calculations involving the stoichiometry of the reaction.