Water has the highest density at nearly ______ Kelvin.
- A.0
- B.227
- C.277
- D.273
Correct answer
Explanation
The correct answer is C, 277. Water is densest at about 4 degrees Celsius, and 4 plus 273 gives roughly 277 kelvin. Most liquids keep shrinking as they cool, but water behaves oddly: below 4 degrees Celsius it starts to expand again because its molecules begin forming the open, hexagonal pattern of ice. This anomalous expansion is why ice is lighter than water and floats, and why a lake freezes from the top while the 4-degree water sinks to the bottom, letting fish survive the winter. Its density at that point is very close to 1 gram per cubic centimetre. D is wrong because 273 kelvin is 0 degrees Celsius, the freezing point, where water is already less dense than at 4 degrees. A is wrong because 0 kelvin is absolute zero, where no liquid water can exist. B is wrong because 227 kelvin is about minus 46 degrees Celsius, far below freezing. Exam tip: maximum density of water at 4 degrees Celsius equals 277 K; freezing at 273 K, boiling at 373 K.
Practice Questions
View allThe fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
Read the full explanation →Which one of the following statements is correct?
- A.Urea is produced in liver.
- 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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Read the full explanation →Which one of the following is the correct sequence of passage of light in a compound microscope?
- 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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Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
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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Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- 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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They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
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