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210 Short question answer on P block elements

P-Block Elements Master Q&A: Groups 13-18 | Chemca.in
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P-Block Elements Q&A Hub

Strictly compiled 210 Questions and Answers for Groups 13 to 18, including major compounds and exceptions.

G-13 G-14 G-15 G-16 G-17 G-18 Compounds Exceptions

210 Q&A on P-Block Elements (JEE/NEET Focus)

    Group 13 Elements (25 Q&A)

    Basic Concepts

  1. Q1: Which elements belong to Group 13 of the periodic table?
    A: Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), and Thallium (Tl).
  2. Q2: What is the general electronic configuration of Group 13 elements?
    A: ns2np1
  3. Q3: Why is boron classified as a metalloid?
    A: Boron exhibits both metallic and non-metallic properties.
  4. Q4: Why does aluminium have a lower density than expected?
    A: Due to its low atomic mass and high metallic bonding leading to a less compact structure.
  5. Q5: Which element in Group 13 shows the highest metallic character?
    A: Thallium (Tl).

    6. Physical Properties

  6. Q6: Why does boron have a high melting point?
    A: Due to its strong covalent bonding in the crystalline structure.
  7. Q7: Which Group 13 element has the lowest melting point?
    A: Gallium (Ga), because of weak metallic bonding.
  8. Q8: What is the oxidation state of Group 13 elements in most compounds?
    A: +3
  9. Q9: Why does thallium show a stable +1 oxidation state?
    A: Due to the inert pair effect.
  10. Q10: How does the ionization energy trend vary in Group 13 elements?
    A: It decreases down the group but Ga has slightly higher IE than Al due to poor shielding by d-electrons.

    11. Chemical Properties & Compounds

  11. Q11: What happens when boron reacts with acids?
    A: Boron does not react directly with acids due to its non-metallic nature.
  12. Q12: Why does Al react with both acids and bases?
    A: Because it is amphoteric in nature.
  13. Q13: Write the reaction of aluminium with sodium hydroxide.
    A: 2Al + 2NaOH + 6H2O → 2Na[Al(OH)4] + 3H2
  14. Q14: Which Group 13 oxide is amphoteric?
    A: Aluminium oxide (Al2O3).
  15. Q15: What is the nature of boron trihalides (BX3)?
    A: They are Lewis acids due to the electron-deficient boron.
  16. Q16: Why is boric acid considered a Lewis acid?
    A: It accepts a pair of electrons from water molecules.
  17. Q17: Give the formula of diborane.
    A: B2H6.
  18. Q18: What is the hybridization of boron in BF3?
    A: sp2
  19. Q19: Why is BF3 more stable than BI3?
    A: Due to strong back bonding in BF3 between boron and fluorine.
  20. Q20: What is the structure of diborane (B2H6)?
    A: It has a three-center two-electron (3c-2e) bond involving hydrogen bridges.

    21. Miscellaneous

  21. Q21: Which Group 13 element is used in thermometers for measuring high temperatures?
    A: Gallium (Ga).
  22. Q22: What is the role of aluminium powder in thermite reactions?
    A: It acts as a reducing agent to produce molten iron.
  23. Q23: Which Group 13 element is used in semiconductors?
    A: Gallium (Ga) in the form of GaAs (Gallium Arsenide).
  24. Q24: Why is aluminium corrosion-resistant?
    A: It forms a protective oxide layer on its surface.
  25. Q25: Which compound of boron is used as a rocket fuel?
    A: Boron hydrides (e.g., diborane, B2H6).

    26. Group 14 Elements (25 Q&A)

    Basic Concepts & Physical Properties

  26. Q26: Which elements belong to Group 14 of the periodic table?
    A: Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn), and Lead (Pb).
  27. Q27: What is the general electronic configuration of Group 14 elements?
    A: ns2np2
  28. Q28: Why does carbon show allotropy?
    A: Due to its ability to form different structural modifications like diamond, graphite, and fullerenes.
  29. Q29: Which is the most metallic element in Group 14?
    A: Lead (Pb).
  30. Q30: Why is silicon a semiconductor?
    A: It has an intermediate band gap (∼ 1.1 eV), allowing controlled electrical conductivity.
  31. Q31: How does atomic size vary down Group 14?
    A: It increases due to the addition of new electron shells.
  32. Q32: Why does carbon have the highest ionization energy in Group 14?
    A: Due to its small atomic size and strong effective nuclear charge.
  33. Q33: Why does lead show a stable +2 oxidation state?
    A: Due to the inert pair effect.
  34. Q34: Which element in Group 14 has the highest melting point?
    A: Carbon (as diamond), due to its strong covalent bonding.
  35. Q35: How does the catenation tendency vary in Group 14 elements?
    A: C > Si > Ge > Sn > Pb (decreases down the group).

    36. Chemical Properties & Compounds

  36. Q36: What happens when carbon reacts with oxygen?
    A: It forms CO2 or CO depending on oxygen availability.
    C + O2 → CO2
    2C + O2 → 2CO
  37. Q37: What is the hybridization of carbon in methane (CH4)?
    A: sp3
  38. Q38: Why is CO2 a gas while SiO2 is a solid?
    A: CO2 has discrete molecules, while SiO2 has a giant covalent network.
  39. Q39: Write the reaction of lead dioxide with hydrochloric acid.
    A: PbO2 + 4HCl → PbCl2 + Cl2 + 2H2O
  40. Q40: What happens when tin reacts with nitric acid?
    A: It forms metastannic acid (H2SnO3).
  41. Q41: What is the structure of graphite?
    A: Hexagonal layers with delocalized π-electrons, making it a good conductor.
  42. Q42: Why does diamond not conduct electricity?
    A: Due to the absence of free electrons, as all valence electrons are involved in covalent bonding.
  43. Q43: What is the nature of CO2 in water?
    A: Weakly acidic, forming carbonic acid (H2CO3).
  44. Q44: What is the hybridization of silicon in SiCl4?
    A: sp3
  45. Q45: Why is lead (II) chloride sparingly soluble in water?
    A: Due to its strong lattice energy.

    46. Applications

  46. Q46: Which compound of silicon is used in waterproofing?
    A: Silicones (Polysiloxanes).
  47. Q47: Which oxide of lead is used in storage batteries?
    A: Lead dioxide (PbO2).
  48. Q48: Why is germanium used in transistors?
    A: Due to its semiconductor properties.
  49. Q49: What is the commercial use of silica (SiO2)?
    A: Glass manufacturing.
  50. Q50: Why is tin used for coating food cans?
    A: It is corrosion-resistant and non-toxic.

    51. Group 15 Elements (25 Q&A)

    Basic Concepts & Physical Properties

  51. Q51: Which elements belong to Group 15 of the periodic table?
    A: Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi).
  52. Q52: What is the general electronic configuration of Group 15 elements?
    A: ns2np3
  53. Q53: Why does nitrogen exist as a diatomic molecule (N2)?
    A: Due to its small size and strong triple bond between nitrogen atoms.
  54. Q54: Which is the most metallic element in Group 15?
    A: Bismuth (Bi).
  55. Q55: Why does nitrogen show catenation less than phosphorus?
    A: Due to weak N-N single bonds caused by strong lone pair-lone pair repulsions.
  56. Q56: How does atomic size vary down Group 15?
    A: It increases due to the addition of new electron shells.
  57. Q57: Why does nitrogen have the highest ionization energy in Group 15?
    A: Due to its small atomic size and strong nuclear attraction.
  58. Q58: Which element in Group 15 is a liquid at room temperature?
    A: None; however, white phosphorus melts at a low temperature (∼ 44°C).
  59. Q59: What is the trend of electronegativity in Group 15?
    A: N > P > As > Sb > Bi.
  60. Q60: Why does nitrogen have a low boiling point?
    A: Because it exists as a small diatomic gas with weak van der Waals forces.

    61. Chemical Properties & Compounds

  61. Q61: What is the common oxidation state of Group 15 elements?
    A: -3, +3, and +5.
  62. Q62: Why is the +5 oxidation state of bismuth less stable?
    A: Due to the inert pair effect.
  63. Q63: What happens when phosphorus reacts with oxygen?
    A: It forms phosphorus oxides: 4P + 5O2 → 2P2O5
  64. Q64: Why does nitrogen form strong hydrogen bonds in compounds like ammonia?
    A: Due to its high electronegativity and small size.
  65. Q65: Write the reaction of ammonia with HCl.
    A: NH3 + HCl → NH4Cl
  66. Q66: Why is white phosphorus more reactive than red phosphorus?
    A: Due to its strained P4 tetrahedral structure.
  67. Q67: What is the hybridization of nitrogen in ammonia (NH3)?
    A: sp3
  68. Q68: Why is phosphine (PH3) a weaker base than ammonia?
    A: Due to the lower electronegativity and larger size of phosphorus.
  69. Q69: What happens when nitric acid decomposes?
    A: It forms nitrogen dioxide (NO2), oxygen, and water.
  70. Q70: Which oxide of nitrogen is neutral?
    A: Nitrous oxide (N2O).

    71. Applications

  71. Q71: Which allotrope of phosphorus is used in safety matches?
    A: Red phosphorus.
  72. Q72: Which compound of nitrogen is used as a fertilizer?
    A: Ammonium nitrate (NH4NO3).
  73. Q73: Why is nitric acid a strong oxidizing agent?
    A: Due to the presence of the NO3− ion, which readily accepts electrons.
  74. Q74: Which Group 15 element is used in semiconductors?
    A: Arsenic (As) in gallium arsenide (GaAs).
  75. Q75: What happens when ammonia is oxidized in the presence of a catalyst?
    A: It forms nitric oxide (NO), a key step in Ostwald’s process: 4NH3 + 5O2 → 4NO + 6H2O

    76. Group 16 Elements (25 Q&A)

    Basic Concepts & Physical Properties

  76. Q76: Which elements belong to Group 16 of the periodic table?
    A: Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Polonium (Po).
  77. Q77: What is the general electronic configuration of Group 16 elements?
    A: ns2np4
  78. Q78: What is the common oxidation state of Group 16 elements?
    A: -2, +4, and +6
  79. Q79: Why does oxygen show a maximum oxidation state of +2 while others show +6?
    A: Due to the absence of d-orbitals in oxygen.
  80. Q80: Which Group 16 element is a metalloid?
    A: Tellurium (Te).
  81. Q81: How does atomic size vary down Group 16?
    A: It increases due to the addition of new electron shells.
  82. Q82: Which is the most electronegative element in Group 16?
    A: Oxygen (O).
  83. Q83: Why does oxygen have a much lower melting point than sulfur?
    A: Oxygen exists as O2 molecules with weak van der Waals forces, while sulfur exists as S8 rings with stronger intermolecular forces.
  84. Q84: Why does the metallic character increase down the group?
    A: Due to decreasing ionization energy and increasing atomic size.
  85. Q85: Which is the most stable oxidation state of polonium?
    A: +4

    86. Chemical Properties & Compounds

  86. Q86: Why is the -2 oxidation state more common in oxygen than in other Group 16 elements?
    A: Due to its high electronegativity and small size.
  87. Q87: What is the hybridization of sulfur in SO2?
    A: sp2
  88. Q88: Write the reaction of oxygen with hydrogen.
    A: 2H2 + O2 → 2H2O
  89. Q89: Why does sulfur show catenation more than oxygen?
    A: Due to stronger S-S bonds compared to weaker O-O bonds.
  90. Q90: What happens when sulfur dioxide is dissolved in water?
    A: It forms sulfurous acid: SO2 + H2O → H2SO3
  91. Q91: Why is hydrogen peroxide (H2O2) a good oxidizing agent?
    A: Due to the presence of an unstable O-O bond that easily breaks to release oxygen.
  92. Q92: What happens when sulfur reacts with oxygen?
    A: It forms sulfur dioxide: S + O2 → SO2
  93. Q93: What is the hybridization of sulfur in SF6?
    A: sp3d2
  94. Q94: Why is H2S a weaker acid than H2Te?
    A: Because the bond strength decreases down the group, making it easier for H2Te to donate protons.
  95. Q95: Why does O3 act as an oxidizing agent?
    A: Due to the easy decomposition of ozone into oxygen and nascent oxygen (O3 → O2 + O).

    96. Applications

  96. Q96: Which compound of sulfur is used in vulcanization of rubber?
    A: Sulfur (S8).
  97. Q97: What is the industrial process for manufacturing sulfuric acid?
    A: Contact Process.
  98. Q98: Which Group 16 element is used in xerography?
    A: Selenium (Se).
  99. Q99: Why is polonium highly radioactive?
    A: Due to its unstable nucleus, which undergoes radioactive decay.
  100. Q100: Why is sulfur dioxide used as a food preservative?
    A: It acts as an antimicrobial and antioxidant agent.

    101. Group 17 Elements (25 Q&A)

    Basic Concepts & Physical Properties

  101. Q101: Which elements belong to Group 17 of the periodic table?
    A: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At).
  102. Q102: What is the general electronic configuration of Group 17 elements?
    A: ns2np5
  103. Q103: Why are Group 17 elements called halogens?
    A: The term "halogen" means "salt-former" because these elements form salts with metals.
  104. Q104: Which is the most electronegative element in Group 17?
    A: Fluorine (F).
  105. Q105: Why does fluorine not show a positive oxidation state?
    A: Due to its high electronegativity and the absence of d-orbitals.
  106. Q106: How does atomic size vary down Group 17?
    A: It increases from fluorine to astatine due to the addition of electron shells.
  107. Q107: Which halogen exists as a liquid at room temperature?
    A: Bromine (Br2).
  108. Q108: How does the boiling point of halogens vary down the group?
    A: It increases due to stronger van der Waals forces.
  109. Q109: What is the physical state of fluorine and chlorine at room temperature?
    A: Both are gases.
  110. Q110: Why does fluorine have the lowest bond dissociation energy among halogens?
    A: Due to strong interelectronic repulsions in the small F2 molecule.

    111. Chemical Properties & Compounds

  111. Q111: What is the common oxidation state of halogens?
    A: -1, but other oxidation states like +1, +3, +5, and +7 are also possible (except for fluorine).
  112. Q112: Why is fluorine the strongest oxidizing agent among halogens?
    A: Due to its high electronegativity, low bond dissociation energy, and strong hydration energy.
  113. Q113: Write the reaction of chlorine with water.
    A: Cl2 + H2O ⇌ HCl + HOCl
  114. Q114: Why is iodine less reactive than chlorine?
    A: Due to its larger atomic size and lower bond dissociation energy.
  115. Q115: What happens when bromine reacts with ammonia?
    A: It forms ammonium bromide: 3Br2 + 8NH3 → 6NH4Br + N2
  116. Q116: Why is hydrogen fluoride (HF) a liquid while hydrogen chloride (HCl) is a gas?
    A: Due to strong hydrogen bonding in HF.
  117. Q117: What is the oxidation state of chlorine in hypochlorous acid (HOCl)?
    A: +1
  118. Q118: What happens when chlorine reacts with sodium hydroxide at cold temperatures?
    A: It forms sodium hypochlorite (NaOCl): Cl2 + 2NaOH → NaCl + NaOCl + H2O
  119. Q119: What is the hybridization of iodine in IF7?
    A: sp3d3
  120. Q120: Why does fluorine not form FCl3 like chlorine forms ClF3?
    A: Due to the absence of d-orbitals in fluorine.

    121. Applications

  121. Q121: Which halogen is used in water purification?
    A: Chlorine (Cl2).
  122. Q122: Which halogen is essential for thyroid function?
    A: Iodine (I2), in the form of iodide ions.
  123. Q123: What is the industrial method for preparing chlorine?
    A: Electrolysis of brine (Chlor-alkali process).
  124. Q124: Which halogen is used in non-stick cookware coatings?
    A: Fluorine (in the form of Teflon, (C2F4)n).
  125. Q125: Why is fluorine stored in metal cylinders coated with nickel?
    A: Because it reacts with glass and most metals.

    126. Group 18 Elements (25 Q&A)

    Basic Concepts & Physical Properties

  126. Q126: Which elements belong to Group 18 of the periodic table?
    A: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).
  127. Q127: What is the general electronic configuration of Group 18 elements?
    A: ns2np6 (except Helium: 1s2).
  128. Q128: Why are Group 18 elements called noble gases?
    A: Because they are chemically inert due to their completely filled valence shell.
  129. Q129: Which noble gas has the smallest atomic size?
    A: Helium (He).
  130. Q130: Which noble gas is radioactive?
    A: Radon (Rn).
  131. Q131: How does atomic size vary down the Group 18 elements?
    A: It increases due to the addition of electron shells.
  132. Q132: Why do noble gases have very low boiling points?
    A: Due to weak van der Waals forces between atoms.
  133. Q133: Which noble gas has the highest ionization energy?
    A: Helium (He).
  134. Q134: How does density change down the group?
    A: It increases from helium to radon.
  135. Q135: Why do noble gases have high stability?
    A: Because of their completely filled valence orbitals and high ionization energy.

    136. Chemical Properties & Compounds

  136. Q136: Why do noble gases show very low reactivity?
    A: Due to their stable electronic configuration and high ionization energy.
  137. Q137: Who discovered noble gas compounds?
    A: Neil Bartlett in 1962.
  138. Q138: Which noble gas forms the most number of compounds?
    A: Xenon (Xe).
  139. Q139: Write the reaction of xenon with fluorine to form xenon hexafluoride.
    A: Xe + 3F2 → XeF6
  140. Q140: What is the oxidation state of xenon in XeF4?
    A: +4
  141. Q141: Why do krypton and xenon form compounds, but argon does not?
    A: Because Kr and Xe have lower ionization energies than argon, making them more reactive.
  142. Q142: What is the shape of XeF4 according to VSEPR theory?
    A: Square planar.
  143. Q143: Name a noble gas compound used in chemical synthesis.
    A: Xenon hexafluoroplatinate (Xe[PtF6]).
  144. Q144: What is the hybridization of xenon in XeF6?
    A: sp3d3
  145. Q145: Write the hydrolysis reaction of XeF4.
    A: XeF4 + 2H2O → XeO2 + 4HF

    146. Applications

  146. Q146: Which noble gas is used in filling balloons?
    A: Helium (He).
  147. Q147: Which noble gas is used in neon signs?
    A: Neon (Ne).
  148. Q148: Why is argon used in welding?
    A: Because it provides an inert atmosphere and prevents oxidation.
  149. Q149: Which noble gas is used in cancer treatment?
    A: Radon (Rn), in radiation therapy.
  150. Q150: Why is xenon used in high-intensity lamps?
    A: Due to its ability to produce bright white light.

    151. Compounds of p-block (35 Q&A)

    Acidic & Basic Strength

  151. Q151: Which is more acidic, H2O or H2S?
    A: H2S is more acidic due to weaker H-S bonds compared to H-O bonds.
  152. Q152: How does acidic strength vary among hydrides of Group 15?
    A: NH3 < PH3 < AsH3 < SbH3 < BiH3 (Acidic strength increases down the group).
  153. Q153: Why is HF a weaker acid than HCl despite fluorine being more electronegative?
    A: Due to strong hydrogen bonding in HF, which makes it difficult to dissociate.
  154. Q154: Which is more basic, NH3 or PH3?
    A: NH3 is more basic due to the higher electron density on nitrogen.
  155. Q155: How does basicity of halide ions change in aqueous solution?
    A: I− < Br− < Cl− < F− (F− is the most basic due to its small size and high charge density).
  156. Q156: Which is more acidic, HClO or HClO4?
    A: HClO4 is more acidic due to higher oxidation state and stronger electron-withdrawing effect.
  157. Q157: Why is boric acid considered a weak acid?
    A: It acts as a Lewis acid by accepting OH− rather than donating H+.
  158. Q158: How does the acidic nature of oxides of nitrogen vary?
    A: N2O < NO < N2O3 < NO2 < N2O5 (Acidic nature increases with oxidation state).
  159. Q159: Why is CO2 acidic while SiO2 is neutral?
    A: CO2 dissolves in water to form carbonic acid, while SiO2 is an acidic oxide but insoluble in water.
  160. Q160: Why is Al(OH)3 amphoteric while NaOH is purely basic?
    A: Al(OH)3 reacts with both acids and bases, whereas NaOH only reacts with acids.

    161. Reducing & Oxidizing Properties

  161. Q161: Which is a stronger reducing agent, H2S or H2O?
    A: H2S, because sulfur is less electronegative than oxygen and readily donates electrons.
  162. Q162: Why is HI a stronger reducing agent than HCl?
    A: Due to the weaker H-I bond, which makes it easier to donate electrons.
  163. Q163: Why is SO2 a reducing agent while SO3 is not?
    A: SO2 can be oxidized to SO3, whereas SO3 is already in its highest oxidation state.
  164. Q164: How does reducing strength vary among halides?
    A: F− < Cl− < Br− < I− (Iodide is the strongest reducing agent).
  165. Q165: Why does NH3 act as a reducing agent but NO2 acts as an oxidizing agent?
    A: NH3 can donate electrons, while NO2 can accept electrons.
  166. Q166: Why is P4 more reactive than N2?
    A: P4 has weaker bonds due to bond strain, while N2 has a strong triple bond.
  167. Q167: Why is ClO2 a strong oxidizing agent?
    A: Due to the presence of chlorine in a high oxidation state (+4).
  168. Q168: Why is XeF6 a strong fluorinating agent?
    A: Due to the high oxidizing power of xenon in a high oxidation state.
  169. Q169: Why is HNO3 a strong oxidizing agent?
    A: Due to the presence of nitrogen in its +5 oxidation state.
  170. Q170: Which is a stronger oxidizing agent, O2 or O3?
    A: O3 (ozone) is stronger due to the release of nascent oxygen.

    171. Amphoteric & Structural Properties

  171. Q171: Which p-block hydroxide shows amphoteric behavior?
    A: Al(OH)3.
  172. Q172: Why is PbO2 amphoteric?
    A: It reacts with both acids and bases to form salts.
  173. Q173: Why does ZnO exhibit amphoteric nature?
    A: It reacts with both HCl (acid) and NaOH (base).
  174. Q174: Which oxide is more amphoteric, Al2O3 or B2O3?
    A: Al2O3, as B2O3 is predominantly acidic.
  175. Q175: Why is Sn(OH)2 amphoteric?
    A: It can react with both acids and bases.
  176. Q176: Why is the bond length of H-F shorter than H-I?
    A: Due to the smaller atomic radius of fluorine.
  177. Q177: Why is the bond angle in H2O less than in NH3?
    A: Due to stronger lone pair repulsions in H2O.
  178. Q178: Why does the bond length of halogens increase down the group?
    A: Due to increasing atomic size.
  179. Q179: Why is the bond angle in ClO2− less than in NO2−?
    A: Due to greater lone pair repulsions in ClO2−.
  180. Q180: Why is the bond length of NO shorter than NO2?
    A: Due to partial double bond character in NO.
  181. Q181: Why is H2O liquid while H2S is a gas?
    A: Due to strong hydrogen bonding in water.
  182. Q182: Why is HF more viscous than HCl?
    A: Due to extensive hydrogen bonding.
  183. Q183: Why is SiH4 less stable than CH4?
    A: Due to weaker Si-H bonds.
  184. Q184: Why does N2 have a triple bond?
    A: Due to effective p-p orbital overlap.
  185. Q185: Why is XeF2 linear in shape?
    A: Due to sp³d hybridization and lone pair repulsions.

    186. Exceptions in p-block (25 Q&A)

    Electronic & Oxidation Exceptions

  186. Q186: Why does boron have an incomplete octet in BF3?
    A: Boron has only 6 valence electrons after bonding, making it electron-deficient.
  187. Q187: Why does aluminum form AlCl3 instead of AlCl?
    A: Due to the higher stability of Al3+ over Al+.
  188. Q188: Why does nitrogen not form pentahalides like PCl5?
    A: Nitrogen lacks vacant d-orbitals, restricting it to a maximum oxidation state of +3.
  189. Q189: Why is the bond angle in NH3 greater than in PH3?
    A: NH3 has stronger lone pair-bond pair repulsions due to higher electronegativity of N.
  190. Q190: Why is O2 a paramagnetic molecule despite having an even number of electrons?
    A: Due to the presence of unpaired electrons in its antibonding molecular orbitals.
  191. Q191: Why does fluorine show only a -1 oxidation state?
    A: Fluorine is the most electronegative element and lacks d-orbitals.
  192. Q192: Why does oxygen show a +2 oxidation state in OF2?
    A: Because fluorine is more electronegative, forcing oxygen into a positive oxidation state.
  193. Q193: Why does Pb exhibit +2 oxidation state more commonly than +4?
    A: Due to the inert pair effect, which stabilizes the lower oxidation state.
  194. Q194: Why does Cl exhibit a +7 oxidation state in HClO4 but not F?
    A: Chlorine has vacant d-orbitals, while fluorine lacks them.
  195. Q195: Why is +3 oxidation state more stable in Tl (Thallium) than +1?
    A: Actually, +1 is more stable due to the inert pair effect.

    196. Bonding & Reactivity Exceptions

  196. Q196: Why is B2H6 (diborane) an exception in bonding?
    A: It has three-center two-electron (3c-2e) bonds instead of normal two-electron bonds.
  197. Q197: Why does diamond have a high melting point despite being covalent?
    A: Due to its strong 3D network of covalent sp³ bonds.
  198. Q198: Why is graphite a good conductor of electricity while diamond is not?
    A: Graphite has delocalized π-electrons due to sp² hybridization.
  199. Q199: Why does SF4 have a see-saw shape instead of tetrahedral?
    A: Due to the presence of a lone pair on sulfur.
  200. Q200: Why does XeF2 have a linear shape despite sp³d hybridization?
    A: Due to the presence of three lone pairs on xenon, which occupy equatorial positions.
  201. Q201: Why is boric acid considered a Lewis acid despite being a weak acid?
    A: It accepts OH− instead of donating H+.
  202. Q202: Why is HF a weaker acid in water but a stronger acid in non-aqueous solvents?
    A: Due to extensive hydrogen bonding in water, reducing its dissociation.
  203. Q203: Why does HNO3 act as both an acid and an oxidizing agent?
    A: It donates H+ and also contains nitrogen in a high oxidation state (+5), making it an oxidizer.
  204. Q204: Why is H2O liquid while H2S is a gas?
    A: Due to strong hydrogen bonding in water.
  205. Q205: Why does SiO2 behave as an acidic oxide while CO2 behaves as a gas?
    A: SiO2 forms a strong covalent network, while CO2 exists as discrete molecules.
  206. Q206: Why does F2 have lower bond dissociation energy than Cl2 despite being smaller?
    A: Due to strong lone pair-lone pair repulsions in fluorine.
  207. Q207: Why does white phosphorus (P4) ignite in air while red phosphorus does not?
    A: White phosphorus is more reactive due to strain in the P4 tetrahedral structure.
  208. Q208: Why is noble gas xenon able to form compounds while helium and neon do not?
    A: Due to lower ionization energy and available d-orbitals in xenon.
  209. Q209: Why is H2O2 unstable and decomposes easily?
    A: Due to weak O-O bond and high tendency to form O2 and H2O.
  210. Q210: Why does ClF3 exist but not FCl3?
    A: Because fluorine cannot expand its octet due to the absence of d-orbitals.

P-Block Comprehensive Quiz (30 MCQs)

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2 comments:

  1. Anonymous17:36

    Thank you, its helpful

    ReplyDelete
  2. CHEMCA Support23:20

    Also read most important reactions in inorganic chemistry https://www.chemca.in/2026/06/100-most-important-inorganic-chemical-reactions-for-jee.html

    ReplyDelete

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