NEET Solved Paper 2017 Question 18
Question: Correct increasing order for the wavelengths of absorption in the visible region for the complexes of $ C{o^{3+}} $ is
Options:
A) $ {{[Co{{(NH _3)}_6}]}^{3+}},{{[Co{{(en)}_3}]}^{3+}},{{[Co{{(H _2O)}_6}]}^{3+}} $
B) $ {{[Co{{(en)}_3}]}^{3+}},{{[Co{{(NH _3)}_6}]}^{3+}},{{[Co{{(H _2O)}_6}]}^{3+}} $
C) $ {{[Co{{(H _2O)}_6}]}^{3+}},{{[Co{{(en)}_3}]}^{3+}},{{[Co{{(NH _3O)}_6}]}^{3+}} $
D) $ {{[Co{{(H _2O)}_6}]}^{3+}},{{[Co{{(NH _3)}_6}]}^{3+}},{{[Co{{(en _3)}_3}]}^{3+}} $
Show Answer
Answer:
Correct Answer: B
Solution:
The order of the ligand in the spectrpcemical series $ H _2O<NH _3<en $
Hence, the wavelength of the light observed will be in the order $ {{[Co{{(H _2O)}_6}]}^{3+}}<{{[Co{{(NH _3)}_6}]}^{3+}}<{{[Co{{(en)}_3}]}^{3+}} $
Thus, wavelength absorbed will be in the opposite order i.e., $ {{[Co{{(en)}_3}]}^{3+}},{{[Co{{(NH _3)}_6}]}^{3+}},{{[Co{{(H _2O)}_6}]}^{3+}} $
