Identify the unsaturated compound that does not give red ppts when treated with____________Ammonical cuprous chloride
Correct answer: D. CH2=CH2
- A. CH3-CH2-CCH (1-Butyne)
- B. CH3-CCH(1-Propyne)
- C. CH3-CH2-CH2CCH(1-Pentyne)
- D. CH2=CH2
Explanation
Terminal alkynes such as 1-butyne, 1-propyne and 1-pentyne contain an acidic terminal hydrogen and form red copper acetylide precipitates with ammoniacal cuprous chloride. Ethene is an alkene and has no terminal alkyne hydrogen, so it does not give this red precipitate. The likely mistake is choosing a terminal alkyne because all the listed compounds are unsaturated, but this test is specific to terminal alkynes.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Alkynes
Alkynes are unsaturated hydrocarbons containing a carbon-carbon triple bond, with sp-hybridised carbon atoms and a linear arrangement around the bond. The content includes nomenclature, preparation, acidity of terminal alkynes, and addition reactions with hydrogen, halogens, hydrogen halides and water, as well as oxidation.
Practise Chemistry of Hydrocarbons
1,091 free Chemistry of Hydrocarbons MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Alkynes questions
Terminal alkynes show acidic character due to:
Terminal alkynes such as ethyne react with ammoniacal silver nitrate to give a precipitate because
Ethyne can be prepared in the laboratory by the action of water on
Which of the following has acidic hydrogen?
Ozonolysis of acetylene gives:
Product formed when 2-pentyne reacts with ozone in the absence of Zinc is __________?