C2H4\mathrm{C}_{2} \mathrm{H}_{4}C2H4
C3H5\mathrm{C}_{3} \mathrm{H}_{5}C3H5
C5H7\mathrm{C}_{5} \mathrm{H}_{7}C5H7
C6H5\mathrm{C}_{6} \mathrm{H}_{5}C6H5
C7H8\mathrm{C}_{7} \mathrm{H}_{8}C7H8