(a) write the possible oxidation and reduction half-reactions that occur when magnesium is immersed in each of the following solutions: (i) hcl, (ii) an hcl solution containing dissolved oxygen, and (iii) an hcl solution containing dissolved oxygen and fe2+ ions. (b) in which of these solutions would you expect the magnesium to oxidize most rapidly? why?

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk