Final answer:
The instrument used 500,000 watt-hours or 500 kilowatt-hours of energy.
Step-by-step explanation:
The energy used in watt-hours can be calculated by multiplying the power (in watts) by the time (in hours). In this case, the instrument uses 250,000 watts over 2 hours, so the energy used is 500,000 watt-hours.
To convert this to kilowatt-hours, we divide the energy in watt-hours by 1,000 since 1 kilowatt is equal to 1,000 watts. Therefore, the energy used is 500 kilowatt-hours.