Which of the following is an aldehyde?
- A.Propanal
- B.Propanol
- C.Propyne
- D.Propanone
Correct answer
Explanation
The correct answer is A, Propanal. The ending 'al' marks an aldehyde, so propanal is the three-carbon aldehyde, CH3CH2CHO.
An aldehyde carries the group -CHO at the end of the carbon chain, with the carbonyl carbon attached to a hydrogen. In the naming system of organic chemistry the suffix tells the family: 'al' for an aldehyde, 'ol' for an alcohol, 'one' for a ketone, 'oic acid' for a carboxylic acid, 'ane' for an alkane, 'ene' for an alkene and 'yne' for an alkyne. Methanal and ethanal are the first two aldehydes of the series.
B is wrong: propanol ends in 'ol', so it is an alcohol with an -OH group. C is wrong: propyne ends in 'yne' and is an alkyne with a triple bond. D is wrong: propanone ends in 'one' and is a ketone, better known as acetone.
Exam tip: al for aldehyde, ol for alcohol, one for ketone, oic acid for carboxylic acid.
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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