317925
How many of the following compounds will have lower boiling points as compared to n-pentane? 2,2-Dimethylpropane, 2-methylpropane. 2-methylbutane, 2,2-dimethylbutane, 2-methylpentane, 2-methylbut-2-ene, pent-2-yne
1 4
2 5
3 3
4 1
Explanation:
Factors that affect boiling point of alkanes are: i. Number of C-atoms: As the no. of C-atom increases, the boiling point increases. ii. Branching: The boiling point decreases with increase in branching in isomeric alkanes. Thus, 2,2-dimethylpropane (282.5 K) , 2-methylbutane ( 301 K ) and 2-methylpropane ( 261.3 K ) will have lower boiling point as compared to n-pentane ( 309.1 K ). Also, boiling points of alkenes and alkynes are higher as compared to corresponding alkanes.
CHXI13:HYDROCARBONS
317926
Assertion : Bond fission of \(\mathrm{C}-\mathrm{C}\) takes place easily than \(\mathrm{C}-\mathrm{H}\). Reason : \(\mathrm{C}-\mathrm{H}\) bond is polar in nature.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
The bond energy of C-C (i.e., \({\text{(s}}{{\text{p}}^{\text{3}}}{\text{ - s}}{{\text{p}}^{\text{3}}}{\text{)}}\) is \(83\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\) and bond energy of \(\mathrm{C}-\mathrm{H}\) (i.e., \(\mathrm{sp}^{3}-\mathrm{s}\) ) is \(99\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\). Thus, fission of \(\mathrm{C}-\mathrm{C}\) bond takes place easily in comparison to \(\mathrm{C}-\mathrm{H}\) bond in alkanes. The electronegativity difference between carbon and hydrogen is small and thus \(\mathrm{C}\) - \(\mathrm{H}\) bond is almost non-polar. So, option (3) is correct.
CHXI13:HYDROCARBONS
317927
Boiling point and melting point of a hydrocarbon chain can be enhanced by:
1 Increasing number of carbon in the chain
2 Enhancing branching in hydrocarbon chain
3 Increasing substitution of carbon chain.
4 Decreasing number of carbon in the chain
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317928
Alkanes would be:
1 relatively much more dense than water
2 relatively less dense than water
3 equal in density to water
4 none of these
Explanation:
Density of hydrocarbons is less than that of water.
317925
How many of the following compounds will have lower boiling points as compared to n-pentane? 2,2-Dimethylpropane, 2-methylpropane. 2-methylbutane, 2,2-dimethylbutane, 2-methylpentane, 2-methylbut-2-ene, pent-2-yne
1 4
2 5
3 3
4 1
Explanation:
Factors that affect boiling point of alkanes are: i. Number of C-atoms: As the no. of C-atom increases, the boiling point increases. ii. Branching: The boiling point decreases with increase in branching in isomeric alkanes. Thus, 2,2-dimethylpropane (282.5 K) , 2-methylbutane ( 301 K ) and 2-methylpropane ( 261.3 K ) will have lower boiling point as compared to n-pentane ( 309.1 K ). Also, boiling points of alkenes and alkynes are higher as compared to corresponding alkanes.
CHXI13:HYDROCARBONS
317926
Assertion : Bond fission of \(\mathrm{C}-\mathrm{C}\) takes place easily than \(\mathrm{C}-\mathrm{H}\). Reason : \(\mathrm{C}-\mathrm{H}\) bond is polar in nature.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
The bond energy of C-C (i.e., \({\text{(s}}{{\text{p}}^{\text{3}}}{\text{ - s}}{{\text{p}}^{\text{3}}}{\text{)}}\) is \(83\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\) and bond energy of \(\mathrm{C}-\mathrm{H}\) (i.e., \(\mathrm{sp}^{3}-\mathrm{s}\) ) is \(99\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\). Thus, fission of \(\mathrm{C}-\mathrm{C}\) bond takes place easily in comparison to \(\mathrm{C}-\mathrm{H}\) bond in alkanes. The electronegativity difference between carbon and hydrogen is small and thus \(\mathrm{C}\) - \(\mathrm{H}\) bond is almost non-polar. So, option (3) is correct.
CHXI13:HYDROCARBONS
317927
Boiling point and melting point of a hydrocarbon chain can be enhanced by:
1 Increasing number of carbon in the chain
2 Enhancing branching in hydrocarbon chain
3 Increasing substitution of carbon chain.
4 Decreasing number of carbon in the chain
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317928
Alkanes would be:
1 relatively much more dense than water
2 relatively less dense than water
3 equal in density to water
4 none of these
Explanation:
Density of hydrocarbons is less than that of water.
317925
How many of the following compounds will have lower boiling points as compared to n-pentane? 2,2-Dimethylpropane, 2-methylpropane. 2-methylbutane, 2,2-dimethylbutane, 2-methylpentane, 2-methylbut-2-ene, pent-2-yne
1 4
2 5
3 3
4 1
Explanation:
Factors that affect boiling point of alkanes are: i. Number of C-atoms: As the no. of C-atom increases, the boiling point increases. ii. Branching: The boiling point decreases with increase in branching in isomeric alkanes. Thus, 2,2-dimethylpropane (282.5 K) , 2-methylbutane ( 301 K ) and 2-methylpropane ( 261.3 K ) will have lower boiling point as compared to n-pentane ( 309.1 K ). Also, boiling points of alkenes and alkynes are higher as compared to corresponding alkanes.
CHXI13:HYDROCARBONS
317926
Assertion : Bond fission of \(\mathrm{C}-\mathrm{C}\) takes place easily than \(\mathrm{C}-\mathrm{H}\). Reason : \(\mathrm{C}-\mathrm{H}\) bond is polar in nature.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
The bond energy of C-C (i.e., \({\text{(s}}{{\text{p}}^{\text{3}}}{\text{ - s}}{{\text{p}}^{\text{3}}}{\text{)}}\) is \(83\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\) and bond energy of \(\mathrm{C}-\mathrm{H}\) (i.e., \(\mathrm{sp}^{3}-\mathrm{s}\) ) is \(99\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\). Thus, fission of \(\mathrm{C}-\mathrm{C}\) bond takes place easily in comparison to \(\mathrm{C}-\mathrm{H}\) bond in alkanes. The electronegativity difference between carbon and hydrogen is small and thus \(\mathrm{C}\) - \(\mathrm{H}\) bond is almost non-polar. So, option (3) is correct.
CHXI13:HYDROCARBONS
317927
Boiling point and melting point of a hydrocarbon chain can be enhanced by:
1 Increasing number of carbon in the chain
2 Enhancing branching in hydrocarbon chain
3 Increasing substitution of carbon chain.
4 Decreasing number of carbon in the chain
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317928
Alkanes would be:
1 relatively much more dense than water
2 relatively less dense than water
3 equal in density to water
4 none of these
Explanation:
Density of hydrocarbons is less than that of water.
317925
How many of the following compounds will have lower boiling points as compared to n-pentane? 2,2-Dimethylpropane, 2-methylpropane. 2-methylbutane, 2,2-dimethylbutane, 2-methylpentane, 2-methylbut-2-ene, pent-2-yne
1 4
2 5
3 3
4 1
Explanation:
Factors that affect boiling point of alkanes are: i. Number of C-atoms: As the no. of C-atom increases, the boiling point increases. ii. Branching: The boiling point decreases with increase in branching in isomeric alkanes. Thus, 2,2-dimethylpropane (282.5 K) , 2-methylbutane ( 301 K ) and 2-methylpropane ( 261.3 K ) will have lower boiling point as compared to n-pentane ( 309.1 K ). Also, boiling points of alkenes and alkynes are higher as compared to corresponding alkanes.
CHXI13:HYDROCARBONS
317926
Assertion : Bond fission of \(\mathrm{C}-\mathrm{C}\) takes place easily than \(\mathrm{C}-\mathrm{H}\). Reason : \(\mathrm{C}-\mathrm{H}\) bond is polar in nature.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but Reason is correct.
Explanation:
The bond energy of C-C (i.e., \({\text{(s}}{{\text{p}}^{\text{3}}}{\text{ - s}}{{\text{p}}^{\text{3}}}{\text{)}}\) is \(83\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\) and bond energy of \(\mathrm{C}-\mathrm{H}\) (i.e., \(\mathrm{sp}^{3}-\mathrm{s}\) ) is \(99\,\,{\text{kcal}}\,\,{\text{mo}}{{\text{l}}^ - }\). Thus, fission of \(\mathrm{C}-\mathrm{C}\) bond takes place easily in comparison to \(\mathrm{C}-\mathrm{H}\) bond in alkanes. The electronegativity difference between carbon and hydrogen is small and thus \(\mathrm{C}\) - \(\mathrm{H}\) bond is almost non-polar. So, option (3) is correct.
CHXI13:HYDROCARBONS
317927
Boiling point and melting point of a hydrocarbon chain can be enhanced by:
1 Increasing number of carbon in the chain
2 Enhancing branching in hydrocarbon chain
3 Increasing substitution of carbon chain.
4 Decreasing number of carbon in the chain
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317928
Alkanes would be:
1 relatively much more dense than water
2 relatively less dense than water
3 equal in density to water
4 none of these
Explanation:
Density of hydrocarbons is less than that of water.
