Why are radio waves safer to humans than X- Rays

How many neutrons does element x if it’s atomic number is 28 and its mass number is 87

Newtons view of arrangement of the universe. don't copy from anywhere.

A6.0-μf air-filled capacitor is connected across a 100-v voltage source. after the source fully charges the capacitor, the capacitor is immersed in transformer oil (of dielectric constant 4.5). how much additional charge flows from the voltage source, which remained connected during the process?