Which one of the following does not represent the salt, Calcium carbonate ?
- A.Lime water
- B.Limestone
- C.Chalk
- D.Marble
Correct answer
Explanation
The correct answer is A, Lime water. Lime water is a solution of calcium hydroxide, Ca(OH)2, not calcium carbonate.
Calcium carbonate, CaCO3, occurs naturally in three common forms: limestone, a sedimentary rock; chalk, a soft, fine-grained limestone made of tiny marine shells; and marble, the metamorphic rock formed when limestone is changed by heat and pressure. Lime water is made by dissolving slaked lime in water. It is used to test for carbon dioxide: when CO2 is passed through it, insoluble calcium carbonate forms and the solution turns milky.
B is wrong because limestone is chiefly calcium carbonate.
C is wrong because chalk is a pure, soft form of calcium carbonate.
D is wrong because marble is recrystallised calcium carbonate.
Exam tip: limestone, chalk and marble are CaCO3; lime water is Ca(OH)2 and turns milky with CO2.
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.
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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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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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