Exam-Style Mock Test | Class 11 Chemistry: Hydrocarbons

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Quiz: Hydrocarbons – Certificate Challenge
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Hydrocarbons – Progressive Test

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1 / 50

1. For Kolbe electrolysis of , the main symmetrical alkane product contains how many carbon atoms?

2 / 50

2. A mixture of and is treated with sodium in dry ether. The main difficulty is that

a) oxygen-containing products must form

b) only one carbon-carbon bond can form

c) only methane and ethane can be produced

d) mixed alkane products can form

3 / 50

3. An ethene-ethyne mixture of is completely hydrogenated to ethane. The same mixture on complete combustion gives of . If the hydrogenation consumes of , the mole ratio of ethene to ethyne in the original mixture is

4 / 50

4. A reaction pathway starts with ethene and gives ethane in one step. The reagent condition most suitable for this conversion is

b) , then

c) cold dilute alkaline

5 / 50

5. A table compares butane conformations.

Row	Dihedral relation of groups	Conformation
P		anti
Q		gauche
R	with eclipsing	fully eclipsed
S		least stable fully eclipsed

The row that needs correction is

a) P

b) R

c) Q

d) S

6 / 50

6. Assertion: Alkane halogenation requires light or heat to start efficiently.
Reason: The first step involves homolytic cleavage of or bonds to form halogen radicals.

a) Assertion is false, but Reason is true

b) Both Assertion and Reason are true, and Reason explains Assertion

c) Both Assertion and Reason are true, but Reason does not explain Assertion

d) Assertion is true, but Reason is false

7 / 50

7. Chlorobenzene undergoes nitration more slowly than benzene, but the products are mainly ortho and para because chlorine is

a) deactivating but ortho-para directing

b) strongly meta-directing like

c) activating and para-directing only

d) activating and meta-directing

8 / 50

8. A combustion-and-hydrogenation analysis of hydrocarbon gives of and of . decolourises bromine water and consumes of on complete hydrogenation. The most suitable formula and class are

a) , alkane

b) , open-chain alkyne

c) , open-chain monoalkene

d) , cycloalkane only

9 / 50

9. A hydrocarbon is named from a parent chain of carbon atoms with only single bonds. The root and suffix combination should be

a) prop +

b) hex +

c) but +

d) pent +

10 / 50

10. In benzene, each carbon atom is generally considered

a) -hybridised and trigonal planar

b) -hybridised and linear

c) -hybridised and tetrahedral

d) unhybridised with no sigma bonds

11 / 50

11. The balanced complete combustion equation for methane is

12 / 50

12. A reaction gives a single monosubstituted product from benzene but gives ortho and para products from toluene under similar electrophilic substitution conditions. The difference arises because

a) benzene lacks aromaticity; toluene has a triple bond

b) benzene undergoes only combustion under all conditions

c) toluene has no ring hydrogens

d) benzene has equivalent hydrogens; methyl directs toluene

13 / 50

13. If of reacts completely with water, the amount of ethyne produced is

14 / 50

14. A table lists possible additions of hydrogen halides to alkenes.

Row	Reaction condition	Major orientation stated
P	, no peroxide	Markovnikov addition
Q	, ordinary ionic condition	Markovnikov addition
R	, peroxide present	anti-Markovnikov addition
S	, peroxide present	always anti-Markovnikov like

The row that needs correction is

a) R

b) Q

c) S

d) P

15 / 50

15. Use the arrangement described below for a benzene ring with two identical substituents.
Case 1: substituents at positions and
Case 2: substituents at positions and
Case 3: substituents at positions and
The names of these relative arrangements, in order, are

a) , ,

b) , ,

c) , ,

d) , ,

16 / 50

16. A compound decolourises both bromine water and dilute alkaline at room temperature. The most likely structural feature in is

a) a carbon-carbon double bond

b) a completely saturated ring with no reaction site

c) only single bonds

d) a sodium carboxylate group

17 / 50

17. A compact case is given below.

An alkane contains both primary and tertiary hydrogen atoms. Under chlorination, several monochloro products are observed. Under bromination, one product from the tertiary position becomes strongly favoured.

The observation is best explained by

a) tertiary hydrogens being absent from the alkane

b) bromination being more selective toward the more stable radical pathway

c) bromination converting the alkane into an alkene before substitution

d) chlorination requiring no radicals at all

18 / 50

18. A structure is written as . Its name is

a) but--ene

b) pent--ene

c) pentane

d) pent--ene

19 / 50

19. A reaction comparison is shown below.

Reaction route	Typical carbon-count effect
P. reduction	carbon skeleton retained
Q. Wurtz reaction with one alkyl halide	alkyl group count effectively doubles
R. Soda-lime decarboxylation	alkane has one carbon fewer than the carboxylate salt

The comparison supports the conclusion that

a) alkyl halide reduction always doubles the chain

b) decarboxylation involves loss of the carboxyl carbon

c) Wurtz reaction always gives one carbon fewer

d) all three routes have the same carbon-count effect

20 / 50

20. In addition of to propyne, , one mole of reagent under ordinary ionic conditions mainly gives

21 / 50

21. Nitration of toluene usually gives mainly

a) benzoic acid only

b) nitrobenzene only

c) ortho- and para-nitrotoluene

d) meta-nitrotoluene only

22 / 50

22. A hydrocarbon has formula . Its straight-chain isomer has a higher boiling point than its highly branched isomer. The best reason is that the straight-chain isomer has

a) greater surface contact

b) a terminal acidic alkyne hydrogen

c) aromatic delocalisation

d) a carbon-carbon double bond

23 / 50

23. Alkynes are hydrocarbons that contain at least one

a) double bond only

b) single bond only

c) single bond

d) triple bond

24 / 50

24. The stability order of the two limiting conformations of ethane is

a) staggered becomes less stable only because it has fewer hydrogens

b) staggered eclipsed

c) eclipsed staggered always

d) eclipsed staggered

25 / 50

25. A reaction record for alkane halogenation is shown below.

Row	Condition or reagent	Interpretation
P	with light	radical substitution may occur
Q	with heat	radical bromination may occur
R	alkane plus	halogen substitution occurs
S	without radical-forming condition	reaction is much less favoured

The row that needs correction is

a) S

b) R

c) P

d) Q

26 / 50

26. A table connects combustion conditions with possible products.

Condition	Likely product pattern
P. Sufficient oxygen	mainly and
Q. Limited oxygen	, soot, or partially oxidised products may form
R. Aromatic-rich fuel with poor air supply	smokier flame is more likely
S. Sufficient oxygen	only metal acetylides form

The row that needs correction is

a) R

b) S

c) P

d) Q

27 / 50

27. A table compares alkane reaction types.

Row	Reaction	Broad description
P	Halogenation under light	free-radical substitution
Q	Nitration or sulfonation of alkanes	substitution under harsh conditions
R	Pyrolysis of higher alkanes	cracking into smaller hydrocarbons
S	Combustion in excess oxygen	formation of only alkyl halides

The row that needs correction is

a) Q

b) P

c) S

d) R

28 / 50

28. The pair and differs mainly in

a) different number of -bonds

b) different carbon skeleton

c) same molecular formula

d) different spatial arrangement

29 / 50

29. The table gives four descriptions. Select the row that gives the best broad classification.

Row	Description	Broad class
P	Open-chain hydrocarbon	Aliphatic
Q	Non-aromatic ring hydrocarbon	Alicyclic
R	Benzene-ring hydrocarbon	Aromatic
S	Hydrocarbon containing oxygen	Saturated

a) R and S only

b) Q and S only

c) P, Q, and R only

d) P and S only

30 / 50

30. A simple orientation of hydrocarbon reactions pairs the family and common reaction tendency as

a) alkanes: substitution; alkenes: addition; benzene: mainly substitution

b) alkenes: no reaction; alkynes: no reaction; alkanes: aromatic substitution

c) alkanes: polymerisation only; alkynes: combustion only; benzene: no reaction

d) alkanes: addition; alkenes: substitution; benzene: ordinary addition

31 / 50

31. A saw-horse representation of ethane is most useful because it

a) converts ethane into a cyclic hydrocarbon

b) shows both carbon atoms from an oblique view

c) removes all hydrogen atoms from the structure

d) proves that ethane contains a double bond

32 / 50

32. A student says, “If a group is deactivating, it must always be meta-directing.” The best correction is that

a) all deactivating groups remove the benzene ring

b) halogens are deactivating but usually ortho-para directing

c) deactivating groups always convert benzene into alkanes

d) the word deactivating means no substitution can ever occur

33 / 50

33. Monosubstitution of benzene gives only one product for a given substituent because

a) benzene contains a terminal triple bond

b) all six hydrogen positions in benzene are equivalent

c) substitution always breaks the ring into open chains

d) benzene has six different ring hydrogens

34 / 50

34. Chlorination of benzene in the presence of mainly gives

a) benzyl alcohol and

b) ethyne and

c) chlorobenzene and

d) cyclohexane and

35 / 50

35. A qualitative test record is given below.

Unknown decolourises bromine water. Unknown does not give a precipitate with ammoniacal . The molecular formula of is , and it is known to be an alkyne.

The most suitable identity of is

a) butane

b) but--yne

c) but--yne

d) benzene

36 / 50

36. The carbon atoms directly involved in the bond of an alkyne are generally

a) -hybridised and tetrahedral

b) -hybridised and linear

c) unhybridised and square planar

d) -hybridised and trigonal planar

37 / 50

37. A sample of ethene is completely converted into polyethene. If ethene molecules are joined in one polymer chain, the number of repeating units in that chain is

38 / 50

38. During complete hydrogenation, of an open-chain hydrocarbon absorbs of at and gives an alkane of formula . The formula of is

39 / 50

39. The role of carbon tetravalency in hydrocarbons is best shown by carbon forming

a) two ionic bonds in every hydrocarbon

b) only one bond with hydrogen

c) four covalent bonds in stable neutral molecules

d) only metallic bonds with other carbon atoms

40 / 50

40. The industrial value of cracking higher alkanes is linked to the fact that it

a) forms only one pure product from each petroleum fraction

b) converts every alkane into benzene under cold conditions

c) converts long chains into smaller fuels and alkene feedstocks

d) removes all carbon atoms as

41 / 50

41. A benzene ring already carrying one group undergoes further substitution. The group is generally

a) a group that removes aromaticity permanently

b) ortho-para directing

c) meta directing only

d) unable to affect orientation in any way

42 / 50

42. In the presence of peroxide, addition of to propene mainly gives

43 / 50

43. Polymerisation of ethene produces polyethene by repeated joining of many ethene molecules through their

a) sodium-carboxylate groups

b) carbon-carbon double bonds

c) benzene rings only

d) carbon-oxygen double bonds

44 / 50

44. Polynuclear aromatic hydrocarbons are best described as aromatic compounds that contain

a) sodium carboxylate groups as the main skeleton

b) fused or multiple aromatic ring systems

c) a single open-chain carbon-carbon triple bond only

d) only one carbon atom and four hydrogen atoms

45 / 50

45. In the potential-energy diagram of ethane conformations, the eclipsed conformation corresponds to

a) zero torsional strain

b) a permanent structural isomer

c) an energy minimum

d) an energy maximum

46 / 50

46. A name-structure comparison gives and . The best interpretation is that

a) they are the same compound because both contain four carbon atoms

b) they are alkenes with formula

c) they are chain isomers with molecular formula

d) they are geometrical isomers around a bond

47 / 50

47. A liquid alkane is shaken with water in a test tube, and two layers form. The alkane layer usually floats because alkanes are generally

a) less dense than water and insoluble in it

b) converted into alcohols by shaking

c) ionic and readily soluble in water

d) denser than water and highly polar

48 / 50

48. A graph compares relative reaction rate for electrophilic substitution of three aromatic compounds: toluene, benzene, and nitrobenzene. The highest bar should correspond to

a) nitrobenzene

b) all three exactly equal

c) benzene

d) toluene

49 / 50

49. A compact reaction case is given below.

Benzene is treated with in the presence of . The product contains one bromine atom attached to the benzene ring.

The most suitable equation pattern is

b) as the usual substitution product

50 / 50

50. A hydrocarbon structure has a five-carbon parent chain and one group attached to carbon . The suitable name is

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Hydrocarbons Mock Test – Class 11 Chemistry

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Hydrocarbons – Progressive Test

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