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

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Q72 jee_main_2024_31_jan_evening Oxygen Family (Group 16 Elements)
Choose the correct statements from the following A. All group 16 elements form oxides of general formula EO_2 and EO_3 where E = S, Se, Te and Po. Both the types of oxides are acidic in nature. B. TeO_2 is an oxidising agent while SO_2 is reducing in nature. C. The reducing property decreases from H_2S to H_2Te down the group. D. The ozone molecule contains five lone pairs of electrons. Choose the correct answer from the options given below:
  • A. text1. A and D only
  • B. text2. B and C only
  • C. text3. C and D only
  • D. text4. A and B only

Solution

### Core Logic (A) All group 16 elements form oxides of the EO_2 and EO_3 type where E = S, Se, Te or Po. These are generally acidic in nature. (Correct) (B) SO_2 is reducing while TeO_2 is an oxidising agent due to the inert pair effect increasing the stability of lower oxidation states down the group. (Correct) (C) The reducing property increases from H_2S to H_2Te down the group because the E-H bond dissociation enthalpy decreases as atomic size increases. (Incorrect) (D) The ozone molecule (O_3) has the structure O=O^+-O^-. Counting the lone pairs: the central oxygen has 1, the double-bonded oxygen has 2, and the single-bonded negatively charged oxygen has 3. Total lone pairs = 1 + 2 + 3 = 6. (Incorrect) ### Step 1: Final Selection Since A and B are the only correct statements, option 4 is the right choice. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: The p-Block Elements
Q76 jee_main_2024_31_jan_evening Group 13 Elements (Boron Family)
Given below are two statements: Statement I: Group 13 trivalent halides get easily hydrolyzed by water due to their covalent nature. Statement II: AlCl_3 upon hydrolysis in acidified aqueous solution forms octahedral [Al(H_2O)_6]^3+ ion. In the light of the above statements, choose the correct answer from the options given below:
  • A. text(1) Statement I is true but statement II is false
  • B. text(2) Statement I is false but statement II is true.
  • C. text(3) Both statement I and statement II are false.
  • D. text(4) Both statement I and statement II are true.

Solution

### Core Logic Statement I: In the trivalent state, most compounds of Group 13 elements (like BCl_3, AlCl_3) are covalent due to small cation size and high charge, and they are readily hydrolysed in water. Thus, Statement I is true. Statement II: Trichlorides on hydrolysis in normal water can form tetrahedral [M(OH)_4]^- species depending on pH, but in an acidified aqueous solution, aluminium forms the octahedral [Al(H_2O)_6]^3+ ion where the hybridization state of Al is sp^3d^2. Thus, Statement II is also true. ### Step 1: Final Conclusion Both Statement I and Statement II are correct, pointing to option (4). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: The p-Block Elements
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

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