the answer is c. chemical because coal stores potential energy in its chemical bonds.
answer: 4 joules
given: charge = 1c
potential difference = 4v
now, we can find the work done is moving a charge across a potential difference. the formula used is:
work done (w) = charge (q) × potential difference (v)
⇒ work done = 1c×4v
= 4 joules