Which of the following sources of energy is/are exhausible? i. Solar ii. Fossil fuels iii. Tidal power

Analyze the question: We need to find which energy sources can be used up (exhaustible), meaning they are non-renewable and finite.

Concept:

• Renewable (inexhaustible) sources are naturally replenished and will not run out in human timescales. Examples are solar, tidal, wind, hydro, and geothermal energy.
• Non-renewable (exhaustible) sources take millions of years to form and will eventually run out. Examples are coal, crude oil, natural gas (fossil fuels), and nuclear fuel such as uranium.

Solution:

• i. Solar comes from the Sun, which will keep radiating for billions of years. It is inexhaustible.
• ii. Fossil fuels (coal, petroleum, natural gas) are formed over millions of years and are consumed faster than they form. They are exhaustible.
• iii. Tidal power comes from the gravitational pull of the Moon and Sun on the oceans, which keeps recurring. It is inexhaustible.

Only (ii) is exhaustible.

Check against the options:

• A. ii and iii: wrong, because tidal is renewable
• B. i and ii only: wrong, because solar is renewable
• C. i and iii only: wrong, because these are both renewable
• D. ii only: correct

Exam tip: Remember that "fossil = finished eventually." If an energy source comes from the Sun, the Moon's pull, wind, or flowing water, it is renewable. If it is dug or drilled out of the ground (coal, oil, gas), it is exhaustible. Nigeria's crude oil is a good everyday example of an exhaustible resource.