下列分子式只表示一种纯净物的是(    )

A.C₂H₆                                  B.C₄H₁₀

C.C₂H₄Cl₂                               D.C

A.C₂H₆                  B.C₄H₁₀                  C.C₅H₁₂                D.C

A.CH₂Br₂                B.C₃H₈                  C.C₄H₁₀                  D.C

A.C                  B.C₂H₅Br                 C.C₂H₄O₂               D.C₆H₁₂O₆

A.C₂H₆                                    B.C₄H₁₀

C.C₂H₄Cl₂                               D.C