# Which contains more molecules, 1.00 mol H_2O_2, 1.00 mol C_2H_6, or 1.00 mol CO?

$6.022 \times {10}^{23}$ molecules.
The number of molecules in a mole is constant and is equal to Avogadro's number : $6.022 \times {10}^{23}$.
Therefore, 1.00 mol of ${H}_{2} {O}_{2}$ or 1.00 mol of ${C}_{2} {H}_{6}$ or 1.00 mol $C O$ all contain the same number of molecules which is $6.022 \times {10}^{23}$ molecules.