Frank Solutions for Chapter 11D Alkynes Class 10 Chemistry ICSE
1. Give the names of the first four members of the homologous series of alkynes.
Answer
First four members of the homologus series of alkynes are :
2. How is ethyne prepared in the laboratory ?
Answer
Ethyne is prepared by the reaction of calcium carbide with water
3. What are addition reactions ? How are addition reactions of ethene different from ethyne ?
Answer
Addition Reactions: The reactions in which molecules of the attacking reagent add across the double or triple bond of an unsaturated compound to yield saturated compound.
In case of ethene the addition occurs due to presence of double bond hence one molecule of the compound is added whereas in case of alkynes there is presence of triple bond hence two molecules of the compound is added.
In case of ethene the addition occurs due to presence of double bond hence one molecule of the compound is added whereas in case of alkynes there is presence of triple bond hence two molecules of the compound is added.
4. Write the equations to show what happens when ethyne gas reacts with
(i) Bromine water
(ii) Excess of hydrochloric acid
(i) Bromine water
(ii) Excess of hydrochloric acid
Answer
5. How will you convert
(i) Ethyne to ethane
(ii) Ethyne to acetaldehyde
(i) Ethyne to ethane
(ii) Ethyne to acetaldehyde
Answer
6. Give two chemical tests to distinguish between ethane and ethyne.
Answer
Two chemical tests to distinguish between ethane and ethyne are :
- Bromine water test
- Baeyers test
7. Give three points to differentiate between saturated and unsaturated hydrocarbons.
Answer
|
S. No. |
Saturated organic compound |
Unsaturated organic compound |
|
1. |
All the four valencies of each carbon atom are satisfied by forming single covalent bonds with carbon and with hydrogen atoms |
The valencies of at least two carbon atoms are not fully satisfied by the hydrogen atoms |
|
2. |
Carbon atoms are joined only by a single covalent bond |
Carbon atoms are joined by double covalent bonds or by triple covalent bonds. |
|
3. |
Less reactive |
More reactive |
8. Write the structural formulae and IUPAC name of the second and third homologues.
Answer
Structural formulae and IUPAC name of Second Homologues :
Propyne
9. Give the reactions of ethyne with
(a) Hydrogen
(b) Water
(c) Bromine
(b) Water
(c) Bromine
Answer
10. Explain the following :
(i) Ethene and ethyne burn with sooty luminous flame
(ii) Ethane does not undergo addition reactions
(iii) Ethyne is used for welding and cutting metals
(i) Ethene and ethyne burn with sooty luminous flame
(ii) Ethane does not undergo addition reactions
(iii) Ethyne is used for welding and cutting metals
Answer
(i) Ethene and ethyne burns with a sooty luminous flame as all the carbon atoms do not get oxidized.
(ii) Ethane does not undergo addition reaction due to absence of double and triple bond.
(iii) Ethyne is used for welding and cutting metals as ethylene produce high temperature.
(ii) Ethane does not undergo addition reaction due to absence of double and triple bond.
(iii) Ethyne is used for welding and cutting metals as ethylene produce high temperature.
11. Write three uses of ethyne .
Answer
Uses of ethyne :
- For welding and cutting metals
- For artificial ripening of fruits
- As a general anaesthetic under the name Naracylene.