Can you please help me in this question? Help would be REALLY appreciated :) An unknown material has a refractive index of 2.78 x106. How fast is light traveling in in this material?

What best describes a sonar wave? transverse and electromagnetic transverse and mechanical longitudinal and electromagnetic longitudinal and mechanical

A175 g lump of molten lead at its melting point (327 c) is placed into 55.0 g of water at 20.0 c. the specific heat of lead is 130.j/kg c and the hf of lead is 20,400 j/kg. when the lead and the water have reached equilibrium, what is the temperature of the mixture?

What are similarities and differences of reflection, refraction, diffraction and absorption?