Which one among the following statements with reference to the properties of water is not correct?
- A.The specific heat of water is abnormally high.
- B.Latent heat of fusion of water is very low.
- C.Density of water is higher than ice.
- D.Pure water is a non-conductor of electricity.
Correct answer
Explanation
The correct answer is B, Latent heat of fusion of water is very low. The statement is false because the latent heat of fusion of ice is high, about 334 joules per gram, or roughly 80 calories per gram. That much heat must be absorbed just to melt ice at 0 °C, which is why ice keeps drinks cold for long. Water's high latent heats and its high specific heat both come from the strong hydrogen bonds between its molecules, which take a lot of energy to loosen or break. Option A is wrong to pick because the statement is true: water's specific heat, about 4.18 joules per gram per kelvin, is unusually high, so seas warm and cool slowly. Option C is wrong to pick because the statement is true: ice is less dense than water, so ice floats. Option D is wrong to pick because the statement is true: pure water has almost no ions and conducts electricity very poorly; dissolved salts make it conduct. Exam tip: latent heat of fusion of ice = 80 cal/g; of vaporisation of water = about 540 cal/g.
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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Liver cells turn the toxic ammonia released from the breakdown of amino acids into urea through the ornithine cycle, also called the urea cycle.
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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It binds oxygen at its iron-containing haem groups and carries some carbon dioxide on its protein chains. Each haemoglobin molecule has four polypeptide chains and four haem groups, and each haem iron can hold one oxygen molecule, forming oxyhaemoglobin in the lungs.
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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