Online Test — Carbon and its Compounds
18 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 18
The electronic configuration of carbon (atomic number 6) is:
2, 8
2, 4
2, 6
2, 2
Explanation: Carbon has 6 electrons arranged as 2, 4 - four in the outer shell.
Question 2 of 18
A covalent bond is formed by:
complete transfer of electrons
sharing of a pair of electrons
loss of protons
gain of neutrons
Explanation: Covalent bonding is the sharing of an electron pair between two atoms.
Question 3 of 18
The property of carbon to form long chains by self-linking is called:
tetravalency
catenation
isomerism
allotropy
Explanation: Catenation is the self-linking of carbon atoms into chains and rings.
Question 4 of 18
Which allotrope of carbon is the hardest natural substance?
graphite
fullerene
diamond
charcoal
Explanation: In diamond each carbon is bonded to four others in a rigid 3-D network, making it the hardest.
Question 5 of 18
Which allotrope conducts electricity because of free electrons?
diamond
graphite
fullerene
none
Explanation: Graphite has one free electron per carbon, so it conducts electricity.
Question 6 of 18
The general formula of an alkyne is:
CnH2n+2
CnH2n
CnH2n-2
CnHn
Explanation: Alkynes contain a triple bond and have the general formula CnH2n-2.
Question 7 of 18
The number of electron pairs shared in a triple bond is:
1
2
3
4
Explanation: A triple bond shares three pairs of electrons, e.g. in ethyne C2H2.
Question 8 of 18
The functional group present in ethanal CH3CHO is:
−OH
−CHO
−COOH
−CO−
Explanation: The -CHO group is the aldehyde functional group.
Question 9 of 18
Two consecutive members of a homologous series differ in molecular mass by:
12 u
14 u
16 u
28 u
Explanation: They differ by a -CH2 unit, whose mass is 12 + 2 = 14 u.
Question 10 of 18
n-Butane and isobutane (both C4H10) are:
isotopes
allotropes
structural isomers
homologues
Explanation: Same molecular formula but different structures means they are structural isomers.
Question 11 of 18
The complete combustion of methane gives:
CO and H2
CO2 and H2O
C and H2O
CO2 only
Explanation: CH4 + 2O2 -> CO2 + 2H2O + heat.
Question 12 of 18
Conversion of vegetable oils to vanaspati ghee uses the reaction:
substitution
combustion
hydrogenation
oxidation
Explanation: Unsaturated oils add hydrogen (hydrogenation) over a nickel catalyst to become saturated ghee.
Question 13 of 18
Ethanol reacts with sodium to liberate:
oxygen
hydrogen
carbon dioxide
chlorine
Explanation: 2C2H5OH + 2Na -> 2C2H5ONa + H2; hydrogen gas is released.
Question 14 of 18
Pure ethanoic acid is called glacial acetic acid because it:
is icy blue
freezes in cold weather
boils very easily
is found in glaciers
Explanation: It freezes to ice-like crystals just below room temperature, hence glacial acetic acid.
Question 15 of 18
The ester formed from ethanoic acid and ethanol is:
CH3COOH
C2H5OH
CH3COOC2H5
CH3COONa
Explanation: Esterification gives ethyl ethanoate, CH3COOC2H5, plus water.
Question 16 of 18
A soap molecule has a hydrophobic part which is the:
ionic head
long hydrocarbon tail
sodium ion
water molecule
Explanation: The long carbon (hydrocarbon) tail is hydrophobic; the ionic head is hydrophilic.
Question 17 of 18
Soaps form an insoluble scum in hard water because hard water contains:
Na+ ions
Ca2+ and Mg2+ ions
K+ ions
H+ ions
Explanation: Calcium and magnesium ions react with soap to give an insoluble scum.
Question 18 of 18
The reaction CH4 + Cl2 → CH3Cl + HCl in sunlight is a:
addition reaction
substitution reaction
oxidation reaction
esterification
Explanation: Chlorine replaces a hydrogen atom of methane - a substitution reaction.