317934
Identify the wrong statement regarding alkanes
1 All alkanes burn in air to give \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\)
2 At room temparature, some alkanes are gases, some are liquids and some are solids
3 Whatever be the molecular weight of alkane, its density is less than water
4 Most of the alkanes are soluble in water.
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317935
Which of the following has maximum melting point?
1 \(\mathrm{C}_{4} \mathrm{H}_{10}\)
2 \(\mathrm{C}_{5} \mathrm{H}_{12}\)
3 \(\mathrm{C}_{6} \mathrm{H}_{14}\)
4 \(\mathrm{C}_{7} \mathrm{H}_{16}\)
Explanation:
Due to syymmetrical crystal structure, \(\mathrm{C}_{6} \mathrm{H}_{14}\) has maximum melting point
CHXI13:HYDROCARBONS
317936
Assertion : \({\text{n}}\)-Butane has higher m.pt. than its next lower alkane, propane. Reason : Melting points of alkanes do not show regular variation with increase in molecular size.
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:
Alkanes with even number of carbon atoms have more symmetrical structures that result in closer packing in the crystal structure as compared to alkanes with odd number of carbon atoms. Therefore, the attractive forces in the former are more and the melting points are higher as compared to the alkanes with odd number of carbon atoms. So, option (2) is correct.
CHXI13:HYDROCARBONS
317937
Increasing order of reduction of alkyl halides with zinc and dilute \(\mathrm{HCl}\) is
1 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br}\)
2 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I
3 \(\mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\mathrm{Cl}\)
4 \(\mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Cl}\)
Explanation:
The reactivity of alkyl halides with \(\mathrm{Zn} /\) \(\mathrm{HCl}\) increases as the strength of the \(\mathrm{C}-\mathrm{X}\) bond decreases.
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CHXI13:HYDROCARBONS
317934
Identify the wrong statement regarding alkanes
1 All alkanes burn in air to give \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\)
2 At room temparature, some alkanes are gases, some are liquids and some are solids
3 Whatever be the molecular weight of alkane, its density is less than water
4 Most of the alkanes are soluble in water.
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317935
Which of the following has maximum melting point?
1 \(\mathrm{C}_{4} \mathrm{H}_{10}\)
2 \(\mathrm{C}_{5} \mathrm{H}_{12}\)
3 \(\mathrm{C}_{6} \mathrm{H}_{14}\)
4 \(\mathrm{C}_{7} \mathrm{H}_{16}\)
Explanation:
Due to syymmetrical crystal structure, \(\mathrm{C}_{6} \mathrm{H}_{14}\) has maximum melting point
CHXI13:HYDROCARBONS
317936
Assertion : \({\text{n}}\)-Butane has higher m.pt. than its next lower alkane, propane. Reason : Melting points of alkanes do not show regular variation with increase in molecular size.
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:
Alkanes with even number of carbon atoms have more symmetrical structures that result in closer packing in the crystal structure as compared to alkanes with odd number of carbon atoms. Therefore, the attractive forces in the former are more and the melting points are higher as compared to the alkanes with odd number of carbon atoms. So, option (2) is correct.
CHXI13:HYDROCARBONS
317937
Increasing order of reduction of alkyl halides with zinc and dilute \(\mathrm{HCl}\) is
1 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br}\)
2 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I
3 \(\mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\mathrm{Cl}\)
4 \(\mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Cl}\)
Explanation:
The reactivity of alkyl halides with \(\mathrm{Zn} /\) \(\mathrm{HCl}\) increases as the strength of the \(\mathrm{C}-\mathrm{X}\) bond decreases.
317934
Identify the wrong statement regarding alkanes
1 All alkanes burn in air to give \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\)
2 At room temparature, some alkanes are gases, some are liquids and some are solids
3 Whatever be the molecular weight of alkane, its density is less than water
4 Most of the alkanes are soluble in water.
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317935
Which of the following has maximum melting point?
1 \(\mathrm{C}_{4} \mathrm{H}_{10}\)
2 \(\mathrm{C}_{5} \mathrm{H}_{12}\)
3 \(\mathrm{C}_{6} \mathrm{H}_{14}\)
4 \(\mathrm{C}_{7} \mathrm{H}_{16}\)
Explanation:
Due to syymmetrical crystal structure, \(\mathrm{C}_{6} \mathrm{H}_{14}\) has maximum melting point
CHXI13:HYDROCARBONS
317936
Assertion : \({\text{n}}\)-Butane has higher m.pt. than its next lower alkane, propane. Reason : Melting points of alkanes do not show regular variation with increase in molecular size.
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:
Alkanes with even number of carbon atoms have more symmetrical structures that result in closer packing in the crystal structure as compared to alkanes with odd number of carbon atoms. Therefore, the attractive forces in the former are more and the melting points are higher as compared to the alkanes with odd number of carbon atoms. So, option (2) is correct.
CHXI13:HYDROCARBONS
317937
Increasing order of reduction of alkyl halides with zinc and dilute \(\mathrm{HCl}\) is
1 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br}\)
2 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I
3 \(\mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\mathrm{Cl}\)
4 \(\mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Cl}\)
Explanation:
The reactivity of alkyl halides with \(\mathrm{Zn} /\) \(\mathrm{HCl}\) increases as the strength of the \(\mathrm{C}-\mathrm{X}\) bond decreases.
317934
Identify the wrong statement regarding alkanes
1 All alkanes burn in air to give \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\)
2 At room temparature, some alkanes are gases, some are liquids and some are solids
3 Whatever be the molecular weight of alkane, its density is less than water
4 Most of the alkanes are soluble in water.
Explanation:
Conceptual Questions
CHXI13:HYDROCARBONS
317935
Which of the following has maximum melting point?
1 \(\mathrm{C}_{4} \mathrm{H}_{10}\)
2 \(\mathrm{C}_{5} \mathrm{H}_{12}\)
3 \(\mathrm{C}_{6} \mathrm{H}_{14}\)
4 \(\mathrm{C}_{7} \mathrm{H}_{16}\)
Explanation:
Due to syymmetrical crystal structure, \(\mathrm{C}_{6} \mathrm{H}_{14}\) has maximum melting point
CHXI13:HYDROCARBONS
317936
Assertion : \({\text{n}}\)-Butane has higher m.pt. than its next lower alkane, propane. Reason : Melting points of alkanes do not show regular variation with increase in molecular size.
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:
Alkanes with even number of carbon atoms have more symmetrical structures that result in closer packing in the crystal structure as compared to alkanes with odd number of carbon atoms. Therefore, the attractive forces in the former are more and the melting points are higher as compared to the alkanes with odd number of carbon atoms. So, option (2) is correct.
CHXI13:HYDROCARBONS
317937
Increasing order of reduction of alkyl halides with zinc and dilute \(\mathrm{HCl}\) is
1 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br}\)
2 \(\mathrm{R}-\mathrm{Cl} < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I
3 \(\mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Br} < \mathrm{R}-\mathrm{Cl}\)
4 \(\mathrm{R}-\mathrm{Br} < \mathrm{R}-\) I \( < \mathrm{R}-\mathrm{Cl}\)
Explanation:
The reactivity of alkyl halides with \(\mathrm{Zn} /\) \(\mathrm{HCl}\) increases as the strength of the \(\mathrm{C}-\mathrm{X}\) bond decreases.