Urea, a commonly used nitrogen-based fertiliser, is prepared by the reaction between ammonia and ______.
- A.carbon dioxide
- B.hydrogen
- C.oxygen
- D.sulphur
Correct answer
Explanation
The correct answer is A, carbon dioxide. Urea is made industrially by reacting ammonia with carbon dioxide under high pressure.
The process runs in two steps: ammonia and carbon dioxide first form ammonium carbamate, which then loses a water molecule to give urea. Its formula is CO(NH2)2 and it carries about 46 per cent nitrogen, the highest of the common solid fertilisers, which is why it is the most used nitrogenous fertiliser in India. The ammonia itself comes from the Haber-Bosch process. Urea also has a place in the history of chemistry as the first organic compound synthesised in a laboratory, by Friedrich Wohler in 1828.
B is wrong: ammonia is itself made from nitrogen and hydrogen, and adding hydrogen gives no urea. C is wrong: ammonia with oxygen gives nitric oxide, a step towards nitric acid. D is wrong: ammonia with sulphuric acid gives ammonium sulphate, a different fertiliser.
Exam tip: Urea - ammonia plus carbon dioxide, formula CO(NH2)2, about 46 per cent nitrogen.
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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