What is the formal charge on the xenon atom (xe) in xef2?

F  is a    group  17   element  which  are  referred  to  as halogens.  hence  requires  one  electrons   to  obtain  octet    electron  configuration.Therefore F  has  -1  charge.  Xe  is  a  group  18  element  which  are  referred  to  as    noble  gas  which  has  octet  electron  configuration but due  to  the two  F-   Xe   has  +2   formal  charges.

While unproven, it uses facts to support part of a conclusion. it is still factual and has predictive power, however.