Wavelength of red light is absorbed by the complex
A
$[Cu(CN)_4]^{2-}$
✓
$[Cu(NH_3)_4]^{2+}$
C
$CuSO_4$
D
$Cu(CN)_2$
✓
Answer
Correct option: B.
$[Cu(NH_3)_4]^{2+}$
b The compound which appears blue green, absorb red light as blue-green is complementary to red colour. Here $[Cu(NH_3)_4]^{2+}$ appears blue-green, so it absorbs red colour.
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