Question

which statement best describes control rods?
○ they are unmovable pieces.
○ they are inert.
○ they supply neutrons to start the nuclear chain reaction.
○ they drive the generator.
done

Explanation:

1. Analyze "They are unmovable pieces": Control rods in nuclear reactors are movable to adjust the reaction rate, so this is incorrect.
2. Analyze "They are inert": Control rods (e.g., made of boron or cadmium) are inert and absorb neutrons to control the nuclear chain reaction, this is correct.
3. Analyze "They supply neutrons...": Neutrons for the chain reaction come from fission, not control rods, so this is incorrect.
4. Analyze "They drive the generator": Control rods don't drive generators; turbines connected to generators are driven by steam from nuclear heat, so this is incorrect.

Answer:

B. They are inert