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physical quantities
Answer & Solution
Correct Answer:
Option
C
Why Option A is incorrect: Physical quantities are measurable by definition. If a property cannot be measured, it cannot be classified as a physical quantity.
Why Option B is incorrect: Physical laws are expressed using physical quantities, but the quantities themselves are not defined by being expressible as a law. For example, mass, length, and time are physical quantities, but they are not laws in themselves.
Why Option C is correct: Every physical quantity can be described completely with a numerical value (magnitude) and a suitable unit of measurement. For instance, 20 kg means "20" is the magnitude and "kg" is the unit—this fully represents the physical quantity (mass).
Why Option D is incorrect: Since option B is not a defining characteristic, both B and C together cannot be correct. Only C correctly describes physical quantities.
Conclusion: A physical quantity is fully defined by its magnitude and unit, so the correct answer is Option C.
Why Option B is incorrect: Physical laws are expressed using physical quantities, but the quantities themselves are not defined by being expressible as a law. For example, mass, length, and time are physical quantities, but they are not laws in themselves.
Why Option C is correct: Every physical quantity can be described completely with a numerical value (magnitude) and a suitable unit of measurement. For instance, 20 kg means "20" is the magnitude and "kg" is the unit—this fully represents the physical quantity (mass).
Why Option D is incorrect: Since option B is not a defining characteristic, both B and C together cannot be correct. Only C correctly describes physical quantities.
Conclusion: A physical quantity is fully defined by its magnitude and unit, so the correct answer is Option C.
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