It means that you consider the elements as a list organized by atomic number, the property is seen to repeat over and over as you move through that list.
Missing questions: "find the speed of the electron".
Solution:
the magnetic force experienced by a charged particle in a magnetic field is given by

where
q is the particle charge
v its velocity
B the magnitude of the magnetic field

the angle between the directions of v and B.
Re-arranging the formula, we find:

and by substituting the data of the problem (the charge of the electron is

), we find the velocity of the electron:
I believe the answer is D, only a small part of it
Power=Energy
72,000/60 = 1200 watts
:)
Explanation:
Fgravity = G*(mass1*mass2)/D²
G is the gravitational constant throughout the universe.
D is the distance between the 2 objects.
the distance is now quadrupled.
Fgravitynew = G*(mass1*mass2)/(4D)² =
= G*(mass1*mass2)/(16D²) =
= (G*(mass1*mass2)/D²) / 16 = Fgravity/16
the new gravitational force will be 179/16 = 11.1875 units