Q: Magnetic resonance imaging devices use what to cool the superconducting magnets?


Read this paragraph and choose the correct option from the provided answers:

Magnetic resonance imaging (NMR) devices use liquid nitrogen to cool the superconducting magnets. Nitrogen is a gas at room temperature and liquefies at -195.8°C. Its neighbor on the periodic table (oxygen) boils at -182.95°C. The interactions between nitrogen molecules (N 2 ) are weaker, so the boiling point is lower. Interactions between non-polar molecules depend on the degree of electron fluctuation within the molecule.

 Choices:

- antifreeze

- dry ice

- fluorocarbons

- liquid nitrogen


A:
liquid nitrogen