Question

Air is not visible because it:
A. Is nearly a perfect transparent substance
B. Neither absorbs or reflects light
C. Transmits whole of light
D. Follows all of the above

Answer 1

Hint:When light (electromagnetic wave) falls on a substance, it absorbs some amount of the light, it reflects some amount of light and transmits the remaining amount of light through it. For a substance to be visible to a human eye, the substance must absorb and reflect some amount of light whose wavelength is within the range of wavelengths of visible light.

Complete answer:
We know that air is present in the surrounding but we cannot see it. This means that the molecules of the air do not reflect or absorb any amount of visible light that falls on them.And as a result, they transmit all of the light through them.Therefore, we can say that air is not visible because it neither absorbs or reflects light that fall on it and transmits the whole light. It is like the light just passes through air.

The substances that cannot be seen by human eyes are termed as transparent substances. Since air is completely invisible, it is a perfectly transparent substance. Therefore, the correct reasons for air been not being visible are options A, B and C.

Hence, the correct option is D.

Note: Some may argue that air is visible or it absorbs and reflects light by giving the example of tyndall effect.Tyndall effect is due to the dust particles present in the air and not due to the air molecules. The dust particles scatter light in different direction.Therefore, the argument is incorrect.