p-Block Elements is a Class 12 Chemistry chapter in the NEET (UG) syllabus. NEET720 has 690 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.
106
easy
473
medium
111
hard
Topics covered
Group 13 elements · Group 14 elements · Group 15 elements · Group 16 elements · Group 17 elements · Group 18 elements · p-Block Elements · Group 13 · Group 15 · Group 16 · Group 17 · Group 18 · Group 14 · Group 13-14 · Group 15-16 · Group 17-18 · Silicates · Boron compounds · Halogen oxoacids · Group 15 oxoacids · Group 16 oxoacids · Xenon compounds · Physical properties of Group 13 · Boric acid applications · Inert pair effect · Reactivity of aluminium · Lewis acid-base adducts · Borax bead qualitative test · Covalent network solids of Group 14 · Zeolite applications · Applications of Group 14 elements · Industrial gas mixtures · Reducing properties of Sn2+ · Nitrogen oxides: N2O · Nitric oxide structure and biological role · Group 15 oxides as desiccants · Applications: red phosphorus in safety matches · Nitrogen fixation and N2 inertness · NH4NO3 structure linking fertiliser and explosive hazard · Ozone depletion mechanism
8 free p-Block Elements practice questions with answers
Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.
Question 1 · easy · Group 13 elements
Which Group 13 element is a metalloid, while all other members of the group are metals?
- A.Aluminium
- B.Boron
- C.Gallium
- D.Thallium
Show answer and explanation
Answer: B. Boron
Boron is the only metalloid (semi-metal) in Group 13; Al, Ga, In, and Tl are all metals.
Boron has a high ionization enthalpy, small size, and forms a covalent network solid with semiconducting properties, placing it as a metalloid at the top of Group 13. From aluminium onward, metallic character dominates because of decreasing ionization enthalpy and increasing atomic size down the group.
Common mistake: Assuming all Group 13 elements behave uniformly as metals from the top of the group.
Question 2 · easy · Group 14 elements
Which oxidation state becomes increasingly stable relative to +4 on descending Group 14 from carbon to lead?
- A.+1, due to decreasing metallic character
- B.+4, because heavier elements are more electropositive
- C.+3, because Group 14 mimics Group 13 lower down the group
- D.+2, due to the inert pair effect
Show answer and explanation
Answer: D. +2, due to the inert pair effect
The inert pair effect causes the ns2 electron pair of the valence shell to resist participation in bonding for heavier p-block elements, so +2 becomes progressively more stable than +4 from Si to Pb, being dominant for Pb.
In Group 14 (C, Si, Ge, Sn, Pb), the ground state configuration is ns2 np2, so the group oxidation state is +4. Down the group, poor shielding by d and f electrons and relativistic contraction cause the ns2 pair to be held more tightly and not used in bonding — the inert pair effect. Consequently PbO (Pb2+) is more stable than PbO2 (Pb4+), while for carbon +4 is overwhelmingly dominant and +2 (as in CO) is comparatively unstable/reducing. This is a key NCERT trend for p-block groups 13-16.
Common mistake: Assuming +4 becomes more stable down the group by analogy with increasing metallic character.
Question 3 · easy · Group 14 elements
Catenation, the self-linking property, is maximum in which Group 14 element and why?
- A.Silicon, because Si-Si bonds are stronger than C-C bonds
- B.Carbon, because the C-C bond is strong and carbon's small size allows effective orbital overlap
- C.Lead, because heavier atoms form more stable long chains
- D.Germanium, because it lies in the middle of the group with balanced properties
Show answer and explanation
Answer: B. Carbon, because the C-C bond is strong and carbon's small size allows effective orbital overlap
Catenation ability depends on bond strength of the element-element single bond; C-C (~348 kJ/mol) is much stronger than Si-Si (~226), Ge-Ge, or Sn-Sn bonds, so carbon shows by far the greatest catenation, enabling the vast diversity of organic compounds.
Catenation is the tendency of atoms of the same element to link via covalent bonds to form chains/rings. Its extent correlates with the element-element single bond enthalpy. Carbon's small atomic size gives effective sideways and head-on orbital overlap, giving a strong C-C bond (~348 kJ/mol) and also strong C-H bonds, together enabling millions of organic compounds. Down the group, bond enthalpy of E-E bonds falls (Si-Si ~226, Ge-Ge ~188, Sn-Sn ~151 kJ/mol) due to increasing atomic size and poorer orbital overlap, so catenation tendency falls sharply: C >> Si > Ge ≈ Sn > Pb (negligible).
Common mistake: Believing catenation increases with atomic size like metallic character does.
Question 4 · easy · Group 14 elements
How does metallic character vary on descending Group 14 from carbon to lead?
- A.It remains constant because all Group 14 elements are metalloids
- B.It decreases steadily from carbon to lead
- C.It increases steadily: carbon is a nonmetal, silicon and germanium are metalloids, and tin and lead are metals
- D.It increases then decreases, peaking at germanium
Show answer and explanation
Answer: C. It increases steadily: carbon is a nonmetal, silicon and germanium are metalloids, and tin and lead are metals
As atomic size increases and ionization enthalpy falls down the group, the elements progressively lose their nonmetallic character: carbon is a nonmetal, Si and Ge are metalloids, and Sn and Pb are metals.
Metallic character depends on the ease of losing electrons, which increases as ionization enthalpy decreases with increasing atomic size down a group. In Group 14, carbon (small size, high IE) is a typical nonmetal forming only covalent compounds; silicon and germanium show intermediate metalloid behaviour (semiconductors); tin and lead have large atomic size, lower ionization enthalpy, and behave as metals, forming cationic species like Sn2+/Pb2+. This mirrors the general periodic trend of increasing metallic character down any p-block group.
Common mistake: Assuming metallic character is uniform or peaks in the middle of the group.
Question 5 · easy · Group 14 elements
Which allotrope of carbon conducts electricity well and is used as electrodes, and why?
- A.Diamond, because its rigid 3D lattice allows free electron movement
- B.Fullerene, because its spherical cage structure traps mobile electrons
- C.Graphite, because each carbon is sp2 hybridized with one delocalized electron per atom free to move within the layers
- D.All carbon allotropes conduct equally well because carbon is a nonmetal with four valence electrons
Show answer and explanation
Answer: C. Graphite, because each carbon is sp2 hybridized with one delocalized electron per atom free to move within the layers
In graphite each carbon is sp2 hybridized, bonded to three neighbours within a hexagonal layer; the fourth electron delocalizes over the layer, giving good electrical conductivity along the layers, unlike diamond where all electrons are localized in sigma bonds.
Diamond: each carbon is sp3 hybridized and forms four strong sigma bonds in a rigid 3D network; there are no free/delocalized electrons, so diamond is an electrical insulator and the hardest known natural substance. Graphite: each carbon is sp2 hybridized, bonded to three other carbons in a planar hexagonal layer; the unhybridized p-orbital electrons delocalize over the whole layer (similar to aromatic systems), giving graphite metallic-like conductivity within layers, while weak van der Waals forces between layers make it soft and a good lubricant. This structure-property link is a classic NCERT fact.
Common mistake: Believing all carbon allotropes share identical electrical behaviour.
Question 6 · easy · Group 14 elements
Consider the following statements about Group 14 elements: (I) Atomic radius increases from C to Pb, though the increase from Si to Ge is small due to d-block contraction before Ge. (II) First ionization enthalpy decreases steadily from C to Pb. (III) Catenation tendency decreases from C to Pb. (IV) Tendency to form the +2 oxidation state increases from C to Pb. Which statements are correct?
- A.I and II only
- B.II, III and IV only
- C.I, III and IV only
- D.I, II, III and IV
Show answer and explanation
Answer: D. I, II, III and IV
All four statements are standard NCERT-level trends for Group 14: radius increases (with a small Si-Ge jump due to intervening d-electrons in Ge), ionization enthalpy falls, catenation weakens down the group, and +2 stability rises due to the inert pair effect.
(I) Atomic radius: C < Si < Ge < Sn < Pb, but the Si-to-Ge increase is small because Ge follows the first d-block series and experiences poor shielding from 3d electrons, contracting its expected size. (II) Ionization enthalpy generally decreases down the group as atomic size increases and shielding improves, despite the same d-block irregularity slightly moderating the Ge value. (III) Catenation tendency (C>>Si>Ge≈Sn>Pb) falls because E-E bond enthalpy decreases with increasing atomic size. (IV) The inert pair effect makes +2 increasingly stable relative to +4 down the group, culminating in Pb2+ being more stable than Pb4+. All four are correct and commonly tested together.
Common mistake: Rejecting statement I or II due to unfamiliarity with the Si-Ge size/IE anomaly.
Question 7 · medium · Group 14 elements
Tin exists as grey tin (alpha form) and white tin (beta form), which interconvert near 13.2°C in a process called tin pest. Which statement about this transformation is correct?
- A.Both forms have identical crystal structures and differ only in colour due to surface oxidation
- B.Grey tin is the metallic, malleable form used to coat cans, while white tin is a brittle nonmetallic form found only at high temperature
- C.Grey tin has a diamond-like cubic covalent structure and is stable below 13.2°C, while white tin has a metallic structure stable above 13.2°C
- D.The transformation is irreversible, so grey tin can never convert back into white tin
Show answer and explanation
Answer: C. Grey tin has a diamond-like cubic covalent structure and is stable below 13.2°C, while white tin has a metallic structure stable above 13.2°C
Below 13.2°C, tin favours the diamond-cubic-structured grey (alpha) allotrope, a brittle semiconductor; above this temperature, the metallic white (beta) allotrope, used for tin plating, is stable. Prolonged cold can convert white tin to crumbling grey tin (tin pest).
Tin shows allotropy driven by temperature. Grey tin (alpha-Sn) adopts a diamond cubic lattice similar to carbon/silicon, is a brittle semiconductor, and is thermodynamically stable below about 13.2°C. White tin (beta-Sn) has a body-centred tetragonal metallic structure, is malleable and a good conductor, and is stable above 13.2°C — this is the familiar form used for tinplating and solder. The alpha-beta transformation is reversible and, historically, exposure of tin objects to prolonged cold caused them to crumble into grey powder (tin pest), famously affecting tin buttons on Napoleon's army uniforms and organ pipes in cold European churches.
Common mistake: Swapping which allotrope (grey vs white) is the metallic, everyday form of tin.
Question 8 · medium · Group 14 elements
Consider the following statements about diamond and graphite: (I) Diamond has a higher density than graphite because its atoms are more closely and rigidly packed in three dimensions. (II) Graphite is a good lubricant because adjacent layers are held together only by weak van der Waals forces and can slide over each other. (III) Diamond is thermodynamically more stable than graphite at room temperature and pressure. (IV) The C-C bond length within a graphite layer (about 141.5 pm) is shorter than the C-C bond length in diamond (about 154 pm). Which of these statements are correct?
- A.I and III only
- B.I, II, III and IV
- C.II and III only
- D.I, II and IV only
Show answer and explanation
Answer: D. I, II and IV only
Diamond is denser due to its rigid 3D sp3 network; graphite lubricates because its layers slide past each other; the in-layer C-C bond in graphite (141.5 pm, with partial double-bond character from delocalization) is shorter than the pure single C-C bond in diamond (154 pm). However, graphite, not diamond, is the thermodynamically stable form at standard conditions (diamond is metastable).
(I) True: diamond's tightly packed tetrahedral 3D network gives it a higher density (~3.51 g/cm3) than graphite's layered structure (~2.26 g/cm3). (II) True: graphite's layers are held by weak van der Waals forces, allowing easy interlayer sliding, which is why it is used as a solid lubricant and pencil 'lead'. (III) False: at room temperature and pressure, graphite is actually the thermodynamically stable allotrope of carbon; diamond is metastable (kinetically stable due to a very high activation energy for conversion) — this is a commonly tested distinction. (IV) True: delocalization within graphite's aromatic-like layers gives partial double-bond character, shortening the C-C bond to about 141.5 pm compared to diamond's pure single bond of about 154 pm. So I, II and IV are correct.
Common mistake: Assuming diamond, being harder and more prized, must also be the thermodynamically stable form at room conditions.
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Questions about p-Block Elements for NEET
How many NEET questions does NEET720 have on p-Block Elements?＋
NEET720 has 690 reviewed practice questions on p-Block Elements (Chemistry): 106 easy, 473 medium and 111 hard. 8 of them are free on this page with full explanations; the rest are available in the app.
Is p-Block Elements a Class 11 or Class 12 chapter for NEET?＋
p-Block Elements is a Class 12 Chemistry chapter in the NEET (UG) syllabus. Read the NCERT chapter first, then practise chapter-wise MCQs and previous-year questions.
How should I practise p-Block Elements for NEET?＋
Attempt the questions below without looking at the options for more than a few seconds, mark your answer, then read the explanation even when you were right. Record every mistake and revisit it after a gap. On NEET720 this happens automatically: wrong answers go to your Mistake Book and are scheduled for spaced revision.
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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (690 active practice questions in this chapter today).