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Which ONE of the structural formulae below represents a secondary alcohol? A B C D - NSC Technical Sciences - Question 1 - 2020 - Paper 2
Question 1
Which ONE of the structural formulae below represents a secondary alcohol? A B C D
Worked Solution & Example Answer:Which ONE of the structural formulae below represents a secondary alcohol? A B C D - NSC Technical Sciences - Question 1 - 2020 - Paper 2
Step 1
Which ONE of the structural formulae below represents a secondary alcohol?
Answer
To determine which of the given structural formulae represents a secondary alcohol, we need to identify the location of the hydroxyl group (-OH) and the carbon atoms bonded to it:
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Identify each option: Review the molecular structures provided in options A, B, C, and D.
- Secondary alcohol: A carbon atom with the hydroxyl group (-OH) attached to it must also be connected to two other carbon atoms.
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Analyze each option:
- Option A: The carbon with the -OH group is connected to one carbon atom, thus it is a primary alcohol.
- Option B: The carbon with the -OH is connected to two other carbon atoms, indicating it is a secondary alcohol.
- Option C: Similar to A, this is a primary alcohol.
- Option D: This structure indicates a ketone, not an alcohol.
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Conclusion: Option B is identified as the correct representation of a secondary alcohol.
Step 2
To which homologous series does dichloromethane belong?
Answer
Dichloromethane (CH2Cl2) is classified under the group of molecules known as haloalkanes. This is because it contains carbon and halogen atoms in its structure without containing hydroxyl (-OH) or carboxyl (-COOH) groups. Therefore, the answer is: C: Haloalkanes.
Step 3
In which ONE of the options below are the intermolecular forces arranged from the weakest to the strongest?
Answer
Intermolecular forces vary in strength, and the correct order from weakest to strongest is:
- London forces - These are the weakest intermolecular forces, existing due to temporary dipoles in molecules.
- Dipole-dipole forces - These occur between polar molecules that have permanent dipoles.
- Hydrogen bonds - A specific and stronger type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen or nitrogen.
Thus, the correct arrangement from weakest to strongest is: D: London forces, dipole-dipole forces, hydrogen bonds.