How do solids, liquids, and gases differ?

Solids, liquids and gases :
In solids the particles like molecules of the substance - are very close to each other. They cannot move far from their positions.  In liquids they are separated by some more distance. SO molecules are freely moving inside liquid.  But in gases the molecules are free to move with in the volume.
Gaseous molecules have higher speeds.

Solids have good conductivity of electricity. Some liquids are also conductive. gases may be less conductive. 

Gases have no shape of their own.  Liquids do not have a shape too.  Solids can have some shape and retain their shape.

Gases and Liquids flow. Solids do not flow.

Many gases may be invisible or may be faint in color.  Visibility of liquids and solids is high.

Gases may not taste. they may smell.  Solids and liquids may taste and may or may not smell.

Solids may be transparent to light or may be opaque.  Gases may be highly transparent to light.

Sound travels in solids faster than in gases.

Letter a, because when there are unlike charges they will always attract to each other.