A mixture of metal atoms that are bonded to one another is known as a: A) valence metal
B) crystal
с) ion
d) alloy

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

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.