Form 3 I.S.

Reactivity: W > V > U

Carbon can reduce the oxides of V and U, but not the oxide of W.
Carbon can reduce the oxides of iron or less reactive metals, but cannot reduce the oxides of metals which are more reactive than iron. Therefore, it can be deduced that W is the most reactive metal among the three metals.

Metal V can displace U from a solution of U
A more reactive metal can displace a less reactive metal from the solution of its salt. Therefore, it can be deduced that V is more reactive than U.

V>U
I am not sure about W. If compound of W can be decomposed by electrolysis , then it is more reactive than V. If it can be decompose by heating , then it is less reactive than U.
According to the rule, a more reactive metal can displace a less reactive metal from its solution. So, V>U.

2008-05-23 19:12:41 補充：
may be there is something wrong with coding
metal V is reactive than U