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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : PH_3 has lower boiling point than NH_3. Reason (R): In liquid state NH_3 molecules are associated through vander waal's forces, but PH_3 molecules are associated through hydrogen bonding. In the light of the above statements, choose the most appropriate answer from the options given below:

Solution & Explanation

### Core Logic NH_3 undergoes extensive intermolecular hydrogen bonding due to the high electronegativity and small size of Nitrogen. PH_3 (Phosphine) molecules are only held together by weak van der Waals (dispersion) forces because Phosphorus is less electronegative and larger, unable to form strong hydrogen bonds. ### Step 1: Evaluate Statements Assertion (A) is correct: PH_3 has a lower boiling point than NH_3 because breaking H-bonds in NH_3 requires more energy. Reason (R) is incorrect: It falsely claims NH_3 has van der Waals association and PH_3 has hydrogen bonding. It is exactly the opposite. ### Pattern Recognition N, O, and F are the only atoms electronegative enough to form stable hydrogen bonds in simple hydrides. Boiling point anomaly: NH_3 > PH_3 purely due to H-bonding in NH_3. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: The p-Block Elements Class 11 Chemistry: Chemical Bonding and Molecular Structure

Reference Study Guides

The P Block Elements

More The p-Block Elements Previous-Year Questions — Page 6

Q61 jee_main_2024_31_jan_morning Group 18 Elements
Give below are two statements: Statement-I: Noble gases have very high boiling points. Statement-II: Noble gases are monoatomic gases. They are held together by strong dispersion forces. Because of this they are liquefied at very low temperature. Hence, they have very high boiling points. In the light of the above statements, choose the correct answer from the options given below:
  • A. textStatement I is false but Statement II is true.
  • B. textBoth Statement I and Statement II are true.
  • C. textStatement I is true but Statement II is false.
  • D. textBoth Statement I and Statement II are false.

Solution

### Core Logic Statement I and II are False. Noble gases have low boiling points. Noble gases are held together by weak dispersion forces. ### Pattern Recognition Noble gases are characterized by extremely weak intermolecular forces (London dispersion forces) because they are monoatomic and non-polar, which directly results in very low boiling and melting points. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: The p-Block Elements
Q79 jee_main_2024_31_jan_morning Group 14 Elements
Consider the oxides of group 14 elements SiO_2, GeO_2, SnO_2, PbO_2, CO and GeO. The amphoteric oxides are
  • A. GeO, GeO_2
  • B. SiO_2, GeO_2
  • C. SnO_2, PbO_2
  • D. SnO_2, CO

Solution

### Core Logic In Group 14 elements, the nature of oxides varies down the group: CO is neutral. CO_2 and SiO_2 are acidic. GeO_2 is distinctly acidic. SnO_2 and PbO_2 are amphoteric. ### Pattern Recognition Tin (Sn) and Lead (Pb) mostly form amphoteric oxides (e.g., SnO, SnO_2, PbO, PbO_2), distinguishing them from the acidic oxides of Carbon and Silicon. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: The p-Block Elements

More The p-Block Elements Questions — jee_main_2024_01_february_morning

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