Online Test — The p-Block Elements (Group 13 & 14)
20 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 20
The valence-shell configuration of Group 13 elements is:
ns2np1
ns2np2
ns2np3
ns1
Explanation: Group 13 (boron family) has three valence electrons: ns2np1.
Question 2 of 20
Diborane contains how many bridging hydrogen atoms?
One
Two
Three
Four
Explanation: Two bridging H atoms form the two 3c-2e banana bonds; the other four H are terminal.
Question 3 of 20
Which element shows the strongest tendency for catenation?
Silicon
Germanium
Carbon
Lead
Explanation: C-C bonds are strongest, so carbon catenates most; the tendency falls down the group.
Question 4 of 20
Orthoboric acid acts as a:
strong acid
weak monobasic Lewis acid
strong base
tribasic acid
Explanation: H3BO3 accepts OH- from water, behaving as a weak monobasic Lewis acid.
Question 5 of 20
The most stable oxidation state of thallium is:
+3
+1
+2
+4
Explanation: Inert pair effect makes Tl+1 more stable than Tl+3.
Question 6 of 20
In graphite each carbon atom is:
sp hybridised
sp2 hybridised
sp3 hybridised
sp3d hybridised
Explanation: Graphite is sp2, forming planar hexagonal layers with delocalised electrons.
Question 7 of 20
Water gas is a mixture of:
CO + N2
CO2 + H2
CO + H2
CH4 + CO2
Explanation: Water (synthesis) gas = CO + H2, made by passing steam over hot coke.
Question 8 of 20
Why is SiO2 a solid while CO2 is a gas?
Si is lighter than C
Si cannot form pπ-pπ bonds, so SiO2 is a network solid
CO2 is ionic
SiO2 is molecular
Explanation: Carbon forms pπ-pπ double bonds (molecular CO2); silicon cannot, giving a giant covalent SiO2 network.
Question 9 of 20
Maximum covalency of boron is:
2
3
4
6
Explanation: Boron lacks valence d-orbitals, so its maximum covalency is 4.
Question 10 of 20
Aluminium dissolving in NaOH gives:
Al(OH)3 + O2
Na[Al(OH)4] + H2
AlCl3 + H2
Al2O3 + H2O
Explanation: 2Al + 2NaOH + 6H2O → 2Na[Al(OH)4] + 3H2; Al is amphoteric.
Question 11 of 20
Buckminsterfullerene is:
C12
C60
C6
graphite
Explanation: C60 is the football-shaped cage allotrope of carbon.
Question 12 of 20
The most stable chloride of lead is:
PbCl4
PbCl2
PbCl3
PbCl5
Explanation: Inert pair effect stabilises Pb2+, so PbCl2 is stable while PbCl4 decomposes.
Question 13 of 20
Ga is smaller than Al because of:
lanthanoid contraction
poor shielding by 3d electrons
larger nuclear charge of Al
inert pair effect
Explanation: The intervening 3d electrons shield poorly (d-block contraction), so Ga is slightly smaller than Al.
Question 14 of 20
Carbon monoxide is poisonous because it:
is acidic
binds haemoglobin more strongly than O2
is a network solid
is basic
Explanation: CO forms stable carboxyhaemoglobin, blocking oxygen transport in blood.
Question 15 of 20
Boron shows a diagonal relationship with:
aluminium
carbon
silicon
nitrogen
Explanation: B resembles Si: both covalent metalloids with weakly acidic oxides and easily hydrolysed chlorides.
Question 16 of 20
Silicones are polymers based on the repeating unit:
SiO2
R2SiO
SiH4
SiC
Explanation: Silicones have the (R2SiO) backbone and are water-repellent.
Question 17 of 20
Which oxide is amphoteric?
CO2
Al2O3
SiO2
B2O3
Explanation: Al2O3 reacts with both acids and bases, hence amphoteric.
Question 18 of 20
On strong heating borax finally gives:
NaOH + B2O3
NaBO2 + B2O3
Na2O + H2
NaBH4
Explanation: Borax bead test: Na2B4O7 → 2NaBO2 + B2O3 (glassy bead).
Question 19 of 20
The terminal B-H bonds in diborane are:
3c-2e bonds
ionic bonds
normal 2c-2e bonds
hydrogen bonds
Explanation: The four terminal B-H bonds are ordinary 2-centre 2-electron covalent bonds.
Question 20 of 20
Which is the most abundant metal in the Earth’s crust?
Iron
Aluminium
Calcium
Sodium
Explanation: Aluminium is the most abundant metal in the crust (third most abundant element).