I believe the answer is A, temperature and number of particles are constant. Correct me if i'm wrong :)
Choice ' C ' is a true statement.
The other choices aren't.
This depends on the direction of the velocity vector to the magnetic field vector. The force is F=q(VxB) ("x" is the cross product.) The max force is when V and B are perpendicular. Then F=qVB = (1.602e-19)(2000)(300) = 9.612e-14 N
Explanation:
0.566kg *(1mol/0.197 kg)= 2.87 mol gold
note how the units cancel out, if the units do not cancel out (kg/kg=1) then u did something wrong