alleryStart learning →Liquid nitrogen is used as an alternate cooling agent. The unit gives its boiling temperature as approximately:
A−40 °C
B−80 °C
C−270 °C
D−196 °C
Answer & Solution
Correct answer: D. −196 °C
1. Liquid nitrogen is an inert cryogenic fluid used to chill mixing water and form ice.
2. The unit reports its boiling temperature as about −196 °C.
3. At a batch plant, liquid nitrogen lances inject directly into the water storage tank.
4. This brings the mixing water down to about 1 °C before charging the mixer.
5. The other temperatures misstate the boiling point of liquid nitrogen.
_Source: IGNOU Concrete Technology, Unit 7 "Concreting Equipment" (Mixers, Cableways, Batchers, Buckets, Pre/Post Cooling)._
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