Other than the X-ray difference , how could be the following pairs of isomers be distinguished from one another by :
`[Cr(NH_(3))_(6)][Cr(NO_(2))_(6)] and [Cr(NH_(3))_(4)(NO_(2))_(2)][Cr(NH_(3))_(2)(NO_(2))_(4)]`

Options

A. cryoscopic method
B. measurement of molar conductance
C. measuring magnetic moment
D. observing their colours.

Answer

B

Explanation

(1) `[Cr(NH_(3))_(6)]^(3+) [Cr(NO_(2))_(6)]^(3-) and [Cr(NH_(3))_(4)(NO_(2))_(2)]^(+)[Cr(NH_(3))_(2)(NO_(2))_(4)]^(-)` have same number of ions, so cryoscopic method can not be used.
(2) Molar conductance depends on the number of ions as well as on the charge on the complexes. `[Cr(NH_(3))_(6)]^(3+) [Cr(NO_(2))_(6)]^(3-) and [Cr(NH_(3))_(4)(NO_(2))_(2)]^(+)[Cr(NH_(3))_(2)(NO_(2))_(4)]^(-)` have same number of ions but different electrical charges.
(3) Both complexes have same number of unpaired electrons, so mesuring magntic moments methods can not be used.
(4) They have similar colour because of the similar conditions.