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Given below are the two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R). Assertion (A): There is a considerable increase in covalent radius from N to P. However from As to Bi only a small increase in covalent radius is observed. Reason (R): covalent and ionic radii in a particular oxidation state increases down the group. In the light of the above statement, choose the most appropriate answer from the options given below:

Solution & Explanation

### Core Logic Assertion (A) is a factual statement directly from NCERT: In Group 15, there is a large increase in covalent radius from Nitrogen to Phosphorus, but from Arsenic to Bismuth, the increase is very small. Reason (R) states that covalent and ionic radii increase down the group. This is a generally true statement. ### Step 1: Explaining the discrepancy While (R) is a true general trend, it does not correctly explain the anomaly highlighted in (A). The correct explanation for the small increase in radius from As to Bi is the poor shielding effect of completely filled d and f-orbitals in the heavier members, leading to a higher effective nuclear charge (Z_eff). ### Final Conclusion Therefore, both (A) and (R) are true, but (R) is not the correct explanation for (A). ### Pattern Recognition Whenever radius anomalies occur in heavier p-block elements (like small increases), the underlying cause is almost always d-block or f-block contraction (poor shielding). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: The p-Block Elements

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_30_jan_morning

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