Question

Bright colors in organic molecules is usually due to

extensive conjugation

nitrogen

impurities

long alkyl chains

Answer 1

ans is A extensive conjugation

Most simple organic compounds, having few multiple bonds and few functional groups, do not absorb visible light, and thus appear as being colorless or white. More complex molecules, having several multiple bonds that are conjugated appear as being colored. For multiple bonds to be conjugated, they must be in an alternating double bond – single bond – double bond, etc arrangement.

The energy of the various colors in the visible spectrum is different depending upon the color. Energy of visible light increases in the following order: red (low energy), orange yellow, green, blue, violet (high energy). A highly conjugated system then might absorb the lower energy portions of the light and reflect what is not absorbed. It is this reflected portion that the eye will perceive as the color of that object. A less highly conjugated system will require the absorption of the higher energy part of the spectrum, allowing the lower energy parts to be reflected to the eye. Note that the color that is reflected is the complementary color of the color that is absorbed. For example if the high energy violet portion of the spectrum is absorbed, its complementary color of yellow is what is observed. If the lower energy blue or green colors are absorbed, the colors orange or red would be observed.