1. Use fleming's Right hand rule , since magnetic field is inwards , so force will be in upward direction.
2. F = BqvsinA
since , A = 90°
F = Bqv , it will experience maximum force .
3. work done = F × D
where , D is the distance it will travel in the B
w = BqvD ,
also , D = v×t
W = Bqv²t , where t is the time taken by the charge to travel a distance D