What is the approximate percentage of corn syrup that would make an isotonic solution for the egg?

This can be answered when you execute the egg osmosis sample. All you have to do is submerge the egg in the corn syrup. Since the corn syrup is more concentrated than the egg, the solute would pass through the egg's cellular membrane. In exchange, the water from the egg would go to the syrup. It will achieve equilibrium when both the egg and the corn syrup would have equal osmotic pressures. The solution would be isotonic at approximately 42% corn syrup.

Ametal with a large number of free flowing electrons most likely has good conductivity