Which metal will replace aluminum in a solution of an aluminum compound

Question

a) barium

b) zinc

c) tin

d) silver

Answer 1

The answer is barium, for the reason given above, but bear in mind that this reaction will not occur in aqueous solution.  You would probably need to use some sort of organic solvent because both barium and nascent aluminum (lacking a protective oxide layer) will react vigorously with water to produce hydrogen gas and the metal hydroxide.

Answer 2

b)zinc because it is above the aluminium in activity series i.e. it is more reactive than aluminium.