Answer: a) 8.2 * 10^-8 N or 82 nN and b) is repulsive
Explanation: To solve this problem we have to use the Coulomb force for two point charged, it is given by:

Replacing the dat we obtain F=82 nN.
The force is repulsive because the points charged have the same sign.
I believe that the best answer among the choices provided by the question is the second choice ,<span>B) radiant energy
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Hope my answer would be a great help for you. If you have more questions feel free to ask here at Brainly.
Answer:
That is, mechanical waves cannot travel through a vacuum. This feature of mechanical waves is often demonstrated in a Physics class. A ringing bell is placed in a jar and air inside the jar is evacuated. Once air is removed from the jar, the sound of the ringing bell can no longer be heard.
When your hand hits the table the table will vibrate and your hand will be numb for two to three seconds