In a region of space there is a uniform magnetic field pointing in the positive z direction. In what direction should a negative charge move to experience a force in the positive x direction

the speed in -y

Explanation:

For this exercise we must use the right hand rule. The motion of a positive charge is given by.

Thumb points in the direction of speed

fingers extended in the direction of the magnetic field, + z axis

the palm in the direction of the force, as the charge is negative in the opposite direction of the force, axis + x

therefore the thumb is in the direction - y

the speed in -y

1/0.14nm = 10^10/1.4 a lot