Which one of the following is known as 'water gas' ?
- A.H2O + CO2
- B.NH3
- C.H2 + N2
- D.CO + H2
Correct answer
Explanation
The correct answer is D, CO + H2. Water gas is a mixture of carbon monoxide and hydrogen, made by passing steam over red-hot coke. The reaction is C + H2O → CO + H2, carried out at about 1,000 degrees Celsius. It is called water gas because it is made from water in the form of steam, and it is also known as synthesis gas or syngas because the mixture is used to make methanol and other hydrocarbons. Both its parts burn, so water gas is a fuel with a high calorific value, burning with a blue flame. When air is blown over hot coke instead, the result is producer gas, a mixture of carbon monoxide and nitrogen with a lower heating value. Option A is wrong because steam and carbon dioxide do not burn and are not a fuel gas. Option B is wrong because NH3 is ammonia, made by the Haber process. Option C is wrong because a hydrogen and nitrogen mixture is the feed for making ammonia, not water gas. Exam tip: water gas = CO + H2; producer gas = CO + N2; coal gas = H2 + CH4 + CO.
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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