If the distance between the particles is halved what will happen to the force?

there is no image by the way so I am unable to see what the particles look like

real, smaller and upside-down.   so the answer should be b.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.