In the Fourier heat equation we have dT/dt = alpha * (d^2T/dx^2), with alpha being the proportionality constant. What I do understand is the relation between derivatives of x and t, but why the proportionality constant? How does it even make sense?

more than, less

less than, more

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.

your answer is c! hope this : )