Amolecule must be nonpolar if the molecule1. is liner2. is neutral3. has ionic and convalent bonding4. has a symmetrical charge distribution

4. has a symmetrical charge distribution

Explanation:

Symmetrical charge distribution in molecules results in the formation non-polar molecules.

For a symmetrical distribution of charge to occur, there must be a sort of sharing of electrons between two atoms. In the case where electrons are transferred, there won't be any need to distribute charges.

When electrons are shared between atoms with similar likeness for the electron, none of the two atoms pulls the electrons more to itself. The electrons are shared evenly and symmetrically between the two atoms. This leaves no charge separation on any of the atom. Therefore, the dipoles in one direction cancels out the dipoles in another direction and this leaves no charge.

This makes the molecule non-polar.

3.2x10^7

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.