Question 4 • 25-26 CHEMISTRY IN THE EARTH SYSTEM S1
A gram of water contains more molecules than a gram of ethanol because a water molecule is lighter: H₂O has a molar mass of about 18 g/mol, while ethanol (C₂H₆O) is about 46 g/mol. The specific-heat values show that water requires more heat per gram for the same temperature increase, so choice A reverses the comparison.
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