Which one of the following is the lowest possible temperature?
- A.0° Celsius
- B.−73° Celsius
- C.−173° Celsius
- D.−273° Celsius
Correct answer
Explanation
The correct answer is D, −273° Celsius. This is absolute zero, more exactly −273.15°C or 0 kelvin, the temperature below which nothing can be cooled.
Temperature measures the random motion of particles. As a substance is cooled its particles move less and less, and at absolute zero they would have the least energy possible. By the third law of thermodynamics absolute zero can be approached but never actually reached; laboratories have come within a tiny fraction of a kelvin of it. The Kelvin scale, proposed by Lord Kelvin, starts at this point, so K = °C + 273.15, and 0 K is the zero of that scale.
A, 0°C, is only the freezing point of water, 273.15 K.
B, −73°C, is about 200 K, far above absolute zero.
C, −173°C, is about 100 K, still well above the lowest possible temperature.
Exam tip: absolute zero is 0 K = −273.15°C = −459.67°F; add 273 to convert Celsius to kelvin.
Practice Questions
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- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
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Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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