Define motivation and distinguish between its intrinsic and extrinsic form?

Motivation is basically what gets you to do something. When you're motivated, you're inspired to do something for a certain reason.

Intrinsic motivation is the want to do something for your satisfaction only. You may do something for no other reason than because you enjoying doing it.

Extrinsic motivation is doing something because of an outside force. For example, you may clean up around the house because your parents offered to up your allowance if you did or take away your phone if you didn't - both extrinsic motivations.

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.