question_answer 58)

  The molecules having dipole moment are.......... (a) 2, 2-Dimethylpropane                                             (b) trans-Pent-2-ene (c) cis-Hex-3-ene                                                             (d) 2, 2, 3, 3-Tetramethylbutane

Answer:

    (b, c) Since the \[+I\] effect of \[C{{H}_{2}}C{{H}_{3}}\] group is higher than that of\[C{{H}_{3}}\] group, therefore, the dipole moment \[C-C{{H}_{3}}\] and\[C-C{{H}_{2}}C{{H}_{3}}\] bonds are unequal. Although these two dipoles oppose each other, yet they do not exactly cancel out each other and hence trans-2-pentene has small but finite dipole moment. In cis-hex-3-ene, although the dipole moments of the two \[C-C{{H}_{2}}C{{H}_{3}}\] bond are equal, but are inclined to each other at an angle of \[60{}^\circ \] and hence have a finite dipole moment.