JEE Main 2023ChemistrySome Basic Concepts of ChemistryMediumNumerical

JEE Main 2023Some Basic Concepts of Chemistry Question with Solution

JEE Main 2023 (25 Jan Shift 2)

Question

Number of hydrogen atoms per molecule of a hydrocarbon A having 85.8% carbon is (Given : Molar mass of A=84 g mol-1 )

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Show full solutionCorrect answer: 12
Correct answer
12

Step-by-step explanation

Using table of empirical formula for the compound:
Element Percentage Mole ratio
C 85.8 85.812=7.15 1
H 14.2 14.21=14.2 2

 

Thus, empirical formula is CH2, empirical molecular mass = 14
Thus, Molecular MassEmpirical Mass = n

14×n=84

n=6

Molecular formula C6H12

 

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About this question

This is a previous-year question from JEE Main 2023, covering the Some Basic Concepts of Chemistry chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.