CBSE Class 10 Science 2023 Outside Delhi Set 1

Question : 20

Total: 39

Assertion (A) : Melting point and boiling point of ethanol are lower than that of sodium chloride.
Reason (R): The forces of attraction between the molecules of ionic compounds are very strong.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of (A).
Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of (A).
Assertion (A) is true, but Reason (R) is false.
Assertion (A) is false, but Reason (R) is true.

Solution:

The melting point and boiling point of ethanol are lower than that of sodium chloride. This is because ethanol is a covalent compound, while sodium chloride is an ionic compound. Covalent compounds have weaker intermolecular forces than ionic compounds, which means less energy is required to break the bonds holding the molecules together. Therefore, covalent compounds tend to have lower melting and boiling points as compared to ionic compounds.

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