JEE Main · 2026 · 04 Apr 2026 · Shift 2 · Some Basic Concepts of Chemistry

Count the total number of atoms in each sample. (A) $2$ mol of cyclohexane ${\mathrm{C}}_6{\mathrm{H}}_{12}$ has $18$ atoms per molecule, i.e. $2\times 18=36$ mol of atoms. (B) $684\mathrm{g}$ of sucrose ${\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}$ ($M=342\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$) is $2$ mol, with $45$ atoms per molecule, i.e. $2\times 45=90$ mol of atoms. (C) $90.8\mathrm{L}$ of ${\mathrm{H}}_2$ at STP ($22.7\mathrm{L}\mathrm{mo}{\mathrm{l}}^{-1}$) is $4$ mol, i.e. $4\times 2=8$ mol of atoms. Thus the increasing-to-decreasing count is $90>36>8$, and the correct order is $\mathrm{B}>\mathrm{A}>\mathrm{C}$.