Base your answer on the equation and diagram below represent an electrochemical cell at 298 K and 1 atmosphere. When the switch is closed, electrons flow from

A) Ag+(aq) to Mg2+(aq)
B) Mg(s) to Ag(s)
C) Ag(s) to Mg(s)
D) Mg2+(aq) to Ag+(aq)

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.

the answer is d. matter from the air combined with the steel wool.