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Which of the following statements about helium is not correct?

1. It is used to create and maintain strong superconducting magnets.
2. It serves as a cryogenic medium for experiments conducted at very low temperatures.
3. It is used to inflate balloons in place of hydrogen because it is lighter and does not catch fire.
4. It is employed in gas-cooled nuclear reactors.

Correct answer: It is used to inflate balloons in place of hydrogen because it is lighter and does not catch fire.

Solution

Helium is denser (heavier) than hydrogen, not lighter; it is used in balloons because it is non-flammable, not because it is lighter. The other statements about superconducting magnets, cryogenics, and gas-cooled reactors are correct.

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