Answer:

Explanation:
for the unit vector, we need to divide the given vector by its norm, because it should be in the SAME direction as the original vector, but of magnitude "1".
We notice that the norm of the given vector is:

Then, the unit vector becomes:

To solve this problem we will apply the concept of centripetal acceleration. This type of acceleration is described as the product between the square of the angular velocity and the turning radius. Mathematically the expression can be expressed as

Here,
Angular velocity
r = Radius
Our values are given as,


Replacing,


Therefore the electron's centripetal acceleration is 