Paper 1 · People, Development and Environment

Given below are two statements, an Assertion (A) and a Reason (R). Choose the correct answer.

Assertion (A):Calorific value is basically about fuel efficiency; fuel efficiency is measured by calorific value.

Reason (R):Calorific value is the amount of heat energy present in food or fuel, determined by the complete combustion of a specified quantity at constant pressure in normal conditions, and its unit is kilojoule per kilogram.

ABoth (A) and (R) are true and (R) is the correct explanation of (A) ✓ Correct

BBoth (A) and (R) are true but (R) is not the correct explanation of (A)

C(A) is true, but (R) is false

D(A) is false, but (R) is true

Correct answer: (A) Both (A) and (R) are true and (R) is the correct explanation of (A)

Explanation

Both statements are true and the reasoning statement correctly explains the assertion.

Statement 1 treats calorific value as the essence of fuel efficiency, since a fuel is judged efficient by the heat it delivers.

Statement 2 defines calorific value as the heat released by complete combustion of a fixed quantity at constant pressure in normal conditions.

Its unit of kilojoule per kilogram measures exactly the heat content that decides efficiency, making the reason the direct cause of the assertion.

This is why a higher-calorific fuel releases more usable energy for the same mass burnt.

Hydrogen and natural gas rank high on calorific value while wood and coal rank lower.

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