The freezing point of a substance is always the melting point of that substance.
A.) lower than
B.) higher than
C.) the same as
D.) it depends on what the substance is.

freezing point is any temperature in which a substance turns into ice and melting point is the point in which a substance changes into liquid from ice..So, the correct ans is A(lower than)

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.