Calcium magnesium potassium and sodium are all electrolytes
true or false

False

Explanation:

Calcium, magnesium, potassium and sodium are metals. Metals can only serve as electrodes. The solution of metals are electrolytes. All the listed metals form solutions which are good electrolytes.

Hence the pure metal is not an electrolyte but a metal solution (usually a metal salt solution) is an electrolyte.