(Solved): Nonane has several isomers. Which of the following condensed formulas is NOT an isomer of nonane? ( ...

Nonane has several isomers. Which of the following condensed formulas is NOT an isomer of nonane? (You may select more than one. Incorrect answers will be penalised.) \( \mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CH}_{3} \) \( \left(\mathrm{CH}_{3}\right)_{3} \mathrm{CHCH}_{2} \mathrm{CH}_{2}\left(\mathrm{C}_{3} \mathrm{H}_{7}\right) \) \( \left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{C}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \) \( \left(\mathrm{CH}_{3}\right)_{2} \mathrm{CCH}_{2} \mathrm{CH}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \)