Hydroelectric power station energy transformation diagram illustrating gravitational potential, kinetic, and electrical energy stages.

Let’s go through each question one by one.

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Question 1: What is the SI unit of energy?

We know that:
- Joule (J) is the standard unit for energy in the International System of Units (SI).
- Newton is for force.
- Ohm is for electrical resistance.
- Watt is for power (energy per second).

So, the correct answer is A. Joule.

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Question 2: Food is needed to supply our bodies with energy. What type of energy is present in food?

Food stores energy in its chemical bonds — like sugar, fats, and proteins. When we digest food, our body breaks those bonds and releases energy.

That’s called chemical potential energy.

Light, heat, and electrical energy are not stored in food directly.

So, the correct answer is D. Chemical potential energy.

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Question 3: Energy changes in a hydroelectricity power station.

Look at the diagram:

- L: Water is high up behind the dam → it has height → so it has gravitational potential energy.
- M: Water is flowing down the slope → it’s moving AND still has some height → so it has both kinetic + gravitational potential energy.
- N: The water hits the turbine and makes it spin → spinning = motion → so this is kinetic energy.
- O: The generator turns the spinning into electricity → sent out via cables → so this is electrical energy.

Now check the table options:

Option B says:
- L: Gravitational Potential ✔
- M: Kinetic + Gravitational Potential ✔
- N: Kinetic ✔
- O: Electrical ✔

Perfect match!

So, the correct answer is B.

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Final Answer:
1. A
2. D
3. B