Which statement best describes the relationship between an object's density and its index of refraction? A. As the physical density of the substance increases, the refractive index increases.

B. As the optical density increases, the refractive index increases

C. As the mass of the object increases the refractive index decreases

D. As the mass per unit volume of the substance increases, the refractive index decreases

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.