How reactive is an atom of sodium(na) and why? a)sodium (na) is very reactive because it does not have enough protons in the nucleus. b)sodium (na) is not very reactive because it can only bond with chlorine (cl) to become salt. c)sodium (na) is not very reactive because it does not have a full valence shell. d)sodium (na) is very reactive because it does not have a full valence shell.

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.