Match List I with List II:

Choose the correct answer from the options given below:

A-II, B-I, C-III, D-IV

The correct answer is option 3. A-II, B-I, C-III, D-IV.

Here is an explanation for matching each complex ion with its corresponding wavelength of light absorption:

Complexes and Their Absorption Wavelengths

A. \([CoCl(NH_3)_5]^{2+}\)

Color: Yellow

Absorption Wavelength: Around 535 nm

This complex absorbs light in the blue region of the spectrum (around 535 nm), and the transmitted or reflected light gives the complex a yellow color. The absorption corresponds to the complementary color of yellow, which is blue.

B. \([Co(NH_3)_5(H_2O)]^{3+}\)

Color: Blue

Absorption Wavelength: Around 500 nm

This complex absorbs light in the orange region of the spectrum (around 500 nm), and the transmitted or reflected light appears blue. The absorption corresponds to the complementary color of blue, which is orange.

C. \([Co(NH_3)_6]^{3+}\)

Color: Pink

Absorption Wavelength: Around 475 nm

This complex absorbs light in the green region of the spectrum (around 475 nm), and the transmitted or reflected light appears pink. The absorption corresponds to the complementary color of pink, which is green.

D. \([Co(CN)_6]^{3-}\)

Color: This complex absorbs light in the UV region.

Absorption Wavelength: Around 310 nm

This complex absorbs in the ultraviolet (UV) region of the spectrum, which is not visible to the human eye. Therefore, this complex may not have a strong visible color.

So, the correct matching is:

A ( \([CoCl(NH_3)_5]^{2+}\) ) → II (535 nm)

B ( \([Co(NH_3)_5(H_2O)]^{3+}\) ) → I (500 nm)

C ( \([Co(NH_3)_6]^{3+}\) ) → III (475 nm)

D ( \([Co(CN)_6]^{3-}\) ) → IV (310 nm)

This matches with option 3: A-II, B-I, C-III, D-IV.