🧪 Chemistry · Class 11 · NEET & JEE
p-Block Elements (Groups 13 & 14) - Practice Questions with Answers 75 free MCQs on p-Block Elements (Groups 13 & 14), each with its own worked answer and explanation. Covers the Boron family (Group 13: B, Al) and the Carbon family (Group 14: C, Si, Ge, Sn, Pb). Key topics include Lewis acid behaviour of BF₃, borax bead test, silicates, silicones, allotropes of carbon, and trends in properties down the group.
Take the timed p-Block Elements (Groups 13 & 14) chapterwise test → 75 practice questions on p-Block Elements (Groups 13 & 14) , sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the p-Block Elements (Groups 13 & 14) notes .
Carbon Allotropes: Diamond vs Graphite Diamond (3D network) Every C is sp³, 4 strong bonds → hardest natural substance Graphite (layered sheets) weak van der Waals (layers slide → lubricant) Each C is sp², hexagonal sheets → conducts electricity along sheets Diamond's rigid 3D tetrahedral network makes it the hardest natural material, while graphite's flat hexagonal sheets are held together only by weak forces, letting them slide past each other (used as a lubricant and in pencils).
Easy - 25 questions Q1.
The first member of each p-block group differs from the rest chiefly because it:
A Has a small size, high electronegativity and no d-orbitals in its valence shellB Has low-lying vacant d-orbitals in its valence shell available for bondingC Shows only the lower oxidation stateD Is always metallic in natureShow answer & explanation →
Q2.
Why does boron always form covalent compounds rather than the B<sup>3+</sup> ion?
A Its atomic size is very largeB The sum of its first three ionisation enthalpies is very highC It has a very low electronegativity and a large atomic radiusD It has filled d-orbitalsShow answer & explanation →
Q3.
Which of the following correctly lists a property that increases down Group 14 from C to Pb?
A Catenation tendencyB Stability of the +4 stateC Metallic characterD ElectronegativityShow answer & explanation →
Q4.
Carbon shows a maximum covalency of four whereas silicon can expand it to six (as in SiF<sub>6</sub><sup>2-</sup>). This is because silicon:
A Is more electronegative than carbonB Forms only ionic compoundsC Has a smaller atomic size than carbonD Has accessible vacant 3d-orbitalsShow answer & explanation →
Q5.
Which statement about inert pair effect in Group 13 is correct?
A The +1 state becomes more stable down the group, Tl<sup>+</sup> being quite stableB The +3 state becomes progressively more stable moving down the groupC Boron commonly shows the +1 stateD Aluminium is most stable in the +1 stateShow answer & explanation →
Q7.
Aluminium (Group 13) forms a thin oxide layer that makes it:
A Corrosion-resistant (passive)B Highly reactive overallC Magnetic in most cases under typical conditionsD Radioactive according to standard textbooksShow answer & explanation →
Q8.
Graphite is a good conductor of electricity because:
A Delocalised pi electrons in the layers are free to moveB It is held together largely by metallic bonding like a true metalC It contains ionic bonds that allow charge carriers to migrateD Most of its valence electrons are fixed within localised sigma bondsShow answer & explanation →
Q12.
Which gas is released when aluminium reacts with dilute hydrochloric acid?
A HydrogenB OxygenC ChlorineD Carbon dioxideShow answer & explanation →
Q13.
Group 13 of the periodic table is also known as the:
A carbon familyB boron familyC nitrogen familyD oxygen familyShow answer & explanation →
Q14.
Group 14 of the periodic table is also known as the:
A boron familyB carbon familyC halogen familyD noble gasesShow answer & explanation →
Q17.
Which Group 14 element is the second most abundant element in the Earth’s crust?
A pure carbonB siliconC metallic tinD heavy leadShow answer & explanation →
Q18.
Graphite conducts electricity well because it possesses:
A delocalised free electronsB only strong ionic bondsC no chemical bonds at allD a metallic ion latticeShow answer & explanation →
Medium - 25 questions Q26.
Diborane is described as electron-deficient. The two bridging B–H–B linkages are best described as:
A Normal two-centre two-electron bondsB Ionic bonds between B<sup>3+</sup> and H<sup>-</sup>C Three-centre two-electron (banana) bondsD Three-centre four-electron bondsShow answer & explanation →
Q27.
Assertion: Anhydrous aluminium chloride exists as a dimer Al<sub>2</sub>Cl<sub>6</sub> in the vapour and non-polar solvents. Reason: Dimerisation lets each aluminium complete its octet through chlorine bridges.
A The assertion is false but the reason is trueB Both statements are true but the reason does not correctly explain the assertionC The assertion is true but the reason is falseD Both assertion and reason are true and the reason explains the assertionShow answer & explanation →
Q28.
Carbon monoxide is a powerful reducing agent used in metallurgy. In the reaction Fe<sub>2</sub>O<sub>3</sub> + 3CO → 2Fe + 3CO<sub>2</sub>, the carbon in CO:
A Is oxidised from +2 to +4B Is reduced from +2 to 0C Remains in the +2 stateD Is oxidised from 0 to +4Show answer & explanation →
Q29.
On warming, the +2 compound SnCl<sub>2</sub> reduces mercuric chloride. This reaction is possible because tin in the +2 state:
A Is a strong oxidising agentB Tends to be oxidised to the more stable +4 state, so it is a reducing agentC Is strongly stabilised in the +2 state by a pronounced inert pair effectD Forms a stable +1 stateShow answer & explanation →
Q30.
Down Group 14, the stability of the +2 oxidation state relative to +4:
A decreasesB increasesC remains constantD drops to zeroShow answer & explanation →
Q31.
BF₃ behaves as a Lewis acid because it has:
A a lone pair available for donationB a very high electronegativity valueC an empty orbital and incomplete octetD a natural ionic bonding characterShow answer & explanation →
Q33.
The tendency of an element to link with itself forming long chains, strongest in carbon, is called:
A allotropyB isomerismC polymerisationD catenationShow answer & explanation →
Q34.
Aluminium oxide (Al₂O₃) is amphoteric, meaning it reacts:
A only with acidsB only with basesC with both acids and basesD with neither acids nor basesShow answer & explanation →
Q35.
Silicones are synthetic polymers built on a backbone of alternating:
A silicon and oxygen atomsB carbon and oxygen atomsC silicon and carbon atomsD boron and oxygen atomsShow answer & explanation →
Q36.
Boric acid, H₃BO₃, is a weak monobasic acid because it:
A donates one proton directlyB releases three protons in waterC is fully ionised in waterD accepts OH⁻ from waterShow answer & explanation →
Q37.
Boron does not readily form a B³⁺ ion because of its:
A large atomic sizeB high ionisation energyC low electronegativityD metallic characterShow answer & explanation →
Q41.
Carbon monoxide is highly poisonous because it:
A acts as a strong acidB binds tightly to haemoglobinC acts as a strong baseD is intensely radioactiveShow answer & explanation →
Q42.
Silicones are water-repellent (hydrophobic) because they carry:
A polar hydroxyl groupsB non-polar alkyl groupsC ionic surface chargesD freely moving metal ionsShow answer & explanation →
Q43.
Aluminium is chosen for overhead electrical cables because it is:
A a very dense metalB a light, good conductorC a strongly magnetic metalD a faintly radioactive metalShow answer & explanation →
Q44.
The increasing stability of the +1 oxidation state down Group 13 is explained by the:
A screening effectB inert-pair effectC shielding of d electronsD lanthanoid contractionShow answer & explanation →
Q46.
Carbon shows far more catenation than silicon because:
A C–C bonds are weakerB C–C bonds are strongerC carbon is a metalD silicon is a gasShow answer & explanation →
Q48.
When carbon dioxide is passed through lime water, the white precipitate formed is:
A calcium oxideB calcium carbonateC calcium hydroxideD calcium chlorideShow answer & explanation →
Q50.
The compound borazine (B₃N₃H₆) is often called:
A inorganic benzeneB liquid diamondC white graphiteD hard waterShow answer & explanation →
Hard - 25 questions Q51.
The order of Lewis acid strength of the boron trihalides is BF<sub>3</sub> < BCl<sub>3</sub> < BBr<sub>3</sub>. The accepted explanation is that:
A Fluorine is the least electronegative halogen and forms the weakest B–X bondB BBr<sub>3</sub> has the smallest halogen atomsC Back-bonding into boron's empty 2p-orbital is strongest in BF<sub>3</sub> and weakest in BBr<sub>3</sub>D The B–Br bond is the most ionicShow answer & explanation →
Q52.
When borax is heated strongly it first swells and then yields a transparent glassy bead. The bead, used in the borax bead test, consists essentially of:
A Boron trioxide onlyB Elemental boron and sodium oxideC Sodium tetraborate decahydrate and some free boronD Sodium metaborate and boric anhydride (NaBO<sub>2</sub> and B<sub>2</sub>O<sub>3</sub>)Show answer & explanation →
Q53.
Carbon dioxide is a discrete linear molecule and a gas, while silicon dioxide is a hard high-melting solid. The fundamental reason is that:
A Carbon forms p-p multiple bonds (O=C=O); silicon forms single Si–O network bondsB Carbon cannot form any double bondsC Silicon is far more electronegative than carbon and forms pi bonds very easilyD CO<sub>2</sub> is ionic whereas SiO<sub>2</sub> is covalentShow answer & explanation →
Q54.
Thallium(I) iodide and thallium(III) iodide differ in a subtle way: TlI<sub>3</sub> is actually thallium(I) triiodide rather than thallium(III) iodide. This is best explained by the fact that:
A Iodine cannot exist as I<sub>3</sub><sup>-</sup>B Tl<sup>3+</sup> is a strong enough oxidant to oxidise I<sup>-</sup>, so the stable species is Tl<sup>+</sup> with I<sub>3</sub><sup>-</sup>C Tl<sup>3+</sup> is much more stable than Tl<sup>+</sup> and cannot oxidise iodide ions in dilute solutionD Thallium does not form any iodideShow answer & explanation →
Q55.
Aluminium reacts with both dilute HCl and aqueous NaOH to liberate dihydrogen, showing that Al<sub>2</sub>O<sub>3</sub> and Al are amphoteric. With excess hot NaOH the aluminium-containing product is:
A Finely divided aluminium metal dust and hydrogenB Aluminium hydrideC Sodium tetrahydroxoaluminate(III), Na[Al(OH)<sub>4</sub>]D Sodium aluminideShow answer & explanation →
Q56.
Boron trifluoride (BF<sub>3</sub>) is a Lewis acid but its Lewis acidity is less than BCl<sub>3</sub>. This is because:
A F's lone pair back-donation into B's empty p orbital reduces electron deficiency more than ClB Fluorine is generally more electronegative, which alone explains the lower acidity in typical laboratory settingsC BCl<sub>3</sub> is a physically larger molecule than BF<sub>3</sub> in every dimension under usual circumstancesD BF<sub>3</sub> has shorter B-F bonds, which alone reduces its Lewis acidity according to most researchersShow answer & explanation →
Q57.
Silicones (polysiloxanes) are used in high-temperature applications because:
A Si-O bonds are stronger than C-C bonds due to partial ionic character and high bond energyB Silicon is generally a more abundant element in the Earth's crust than carbon in the majority of cases studiedC They happen to be optically transparent across the visible spectrum as widely reportedD They possess an unusually low viscosity at high temperature in standard practice under most conditions encounteredShow answer & explanation →
Q58.
Fullerene C<sub>60</sub> (Buckminsterfullerene) consists of:
A 20 hexagons and 12 pentagons in a soccer ball arrangementB Sixty separate hexagonal rings with little pentagons presentC Twelve pentagonal rings alone with little hexagons in the structureD A diamond-like cubic lattice of sp<sup>3</sup>-hybridised carbon atomsShow answer & explanation →
Q59.
Carbon exists as diamond (sp<sup>3</sup>) and graphite (sp<sup>2</sup>). The allotrope graphene is:
A A single layer of graphite with exceptional electrical, mechanical, and thermal propertiesB A fully three-dimensional covalent network of carbon identical to diamond's structureC A disordered amorphous carbon form lacking any long-range crystalline structureD A closed, curved carbon sheet resembling a hollow soccer-ball-shaped sphereShow answer & explanation →
Q60.
The correct order of stability of the +2 oxidation state for Ge, Sn and Pb is:
A Ge > Sn > PbB Pb > Sn > GeC Sn > Pb > GeD Ge > Pb > SnShow answer & explanation →
Q61.
Anhydrous AlCl₃ exists as the dimer Al₂Cl₆, in which each aluminium attains:
A an octet using chlorine bridgesB an incomplete electron sextet stillC the unstable +1 oxidation stateD an sp hybridised geometryShow answer & explanation →
Q62.
Diborane (B₂H₆) is termed an electron-deficient molecule because it has:
A far more electrons than it needsB too few electrons for its normal bondsC entirely pure ionic bondingD effectively no bonding at allShow answer & explanation →
Q64.
On descending Group 14 from carbon to lead, the metallic character:
A decreasesB increasesC stays constantD disappearsShow answer & explanation →
Q65.
Tin exists mainly in the ___ state, whereas lead is more stable in the ___ state:
A +2 and +4B +4 and +2C +2 and +2D +4 and +4Show answer & explanation →
Q66.
The reaction of aluminium with hot aqueous sodium hydroxide produces:
A aluminium metal and waterB sodium aluminate and hydrogenC only solid aluminaD aluminium chloride saltShow answer & explanation →
Q67.
In the giant covalent structure of silica (SiO₂), each silicon atom is bonded to:
A two oxygensB three oxygensC four oxygensD six oxygensShow answer & explanation →
Q68.
A molecule of fullerene (C₆₀) has a cage shape resembling a:
A a flat carbon sheetB a football-like cageC a long straight chainD a simple cubic blockShow answer & explanation →
Q70.
Anhydrous AlCl₃ is a covalent dimer, but when dissolved in water it behaves as:
A a purely covalent liquidB an ionic electrolyteC a solid metallic conductorD a chemically inert gasShow answer & explanation →
Q71.
Alumina dissolves in both acids and alkalis, which shows that it is:
A purely acidicB amphotericC purely basicD fully neutralShow answer & explanation →
Q72.
Gallium is unusual among metals because it:
A is a gas at room temperatureB melts in the warmth of a handC is quite strongly radioactiveD is clearly ferromagneticShow answer & explanation →
Q73.
Lead pipes are avoided for carrying drinking water because lead is:
A very expensiveB toxic to humansC strongly magneticD radioactiveShow answer & explanation →
Q74.
Silicones are used as sealants, water-proofing agents and lubricants because of their:
A considerable chemical reactivityB heat stability and water repellenceC a purely ionic bonding natureD a notably strong acidityShow answer & explanation →
Q75.
The relative stability of the +4 oxidation state among Group 14 elements follows the order:
A Pb > Sn > Ge > SiB Si > Ge > Sn > PbC Ge > Si > Pb > SnD Sn > Pb > Si > GeShow answer & explanation →