chemistry MCQs - 12th class Chapter 08 Mcqs

1

Hydrocarbons containing only carbon and hydrogen are known as?

A

Polymers

B

Organic Compounds

C

Isomers

D

Inorganic Compounds

2

The property of carbon atoms to link with one another to form long chains and rings is called?

A

Isomerism

B

Polymerization

C

Catenation

D

Hydrogenation

3

Unsaturated hydrocarbons containing a double bond are called?

A

Alkanes

B

Alkynes

C

Alkenes

D

Cycloalkanes

4

Methane is commonly known as marsh gas because it is found in?

A

Volcanoes

B

Marshy places

C

Coal mines

D

Natural gas reserves

5

According to IUPAC rules, the parent name of an alkane is determined by?

A

The number of branches

B

The longest continuous chain of carbon atoms

C

The type of substituents

D

The presence of a functional group

6

The prefix 'iso' is used in common names to denote a structure with?

A

A straight chain

B

A methyl group on the second-to-last carbon of a continuous chain

C

A carbon atom bonded to four other carbon atoms

D

Two methyl groups on the same carbon

7

When one hydrogen atom is removed from an alkane, the resulting group is called?

A

An alkene

B

An alkyne

C

An alkyl group

D

A functional group

8

In IUPAC nomenclature, how are numbers separated from words in a compound's name?

A

By a comma

B

By a space

C

By a hyphen

D

By a colon

9

If two or more identical substituents are present in an alkane, what prefix is used?

A

Mono

B

Iso

C

Neo

D

Di, tri, tetra

10

When numbering the longest chain of an alkene, where should you start?

A

From the end closest to the substituent

B

From the end closest to the double bond

C

From the left side

D

From the right side

11

The hydrogenation of alkenes in the presence of a Nickel catalyst is known as?

A

Wurtz Reaction

B

Kolbe's Electrolytic Method

C

Sabatier-Sendren's Reaction

D

Grignard Reaction

12

The production of vegetable ghee from vegetable oil is an example of?

A

Halogenation

B

Combustion

C

Catalytic hydrogenation

D

Nitration

13

The elimination of CO2 from the sodium salt of a fatty acid when heated with soda-lime is called?

A

Decarboxylation

B

Hydrogenation

C

Oxidation

D

Polymerization

14

Which method is only suitable for the preparation of symmetrical alkanes (R-R)?

A

Sabatier-Sendren's Reaction

B

Decarboxylation

C

Kolbe's Electrolytic Method

D

From Grignard Reagents

15

Which alkane cannot be prepared using Kolbe's electrolytic method?

A

Ethane

B

Propane

C

Butane

D

Methane

16

The reduction of an aldehyde or ketone to an alkane using zinc amalgam and HCl is called?

A

Wolf-Kishner reduction

B

Clemmensen reduction

C

Baeyer's test

D

Ozonolysis

17

Alkanes are generally insoluble in which type of solvent?

A

Non-polar solvents

B

Benzene

C

Ether

D

Polar solvents like water

18

How does the boiling point of alkanes change with an increase in the number of carbon atoms?

A

It decreases

B

It remains constant

C

It increases

D

It fluctuates

19

The boiling points of branched-chain alkanes are _________ than their straight-chain isomers.

A

Higher

B

Lower

C

The same

D

Unpredictable

20

The unreactivity of alkanes is primarily due to the non-polarity of C-H and C-C bonds and the inertness of the?

A

π-bond

B

Double bond

C

Triple bond

D

σ-bond

21

Complete combustion of an alkane yields?

A

Carbon monoxide and water

B

Carbon dioxide and hydrogen

C

Carbon dioxide and water

D

Carbon black and water

22

Vapour-phase nitration of alkanes occurs under what conditions?

A

Room temperature

B

Low temperature and pressure

C

Drastic conditions (400-500 °C)

D

In the presence of a catalyst

23

The reaction of alkanes with halogens in the presence of UV light proceeds through which mechanism?

A

Electrophilic addition

B

Nucleophilic substitution

C

Free radical mechanism

D

Elimination reaction

24

What is the order of reactivity of halogens with alkanes?

A

F₂ > Cl₂ > Br₂ > I₂

B

I₂ > Br₂ > Cl₂ > F₂

C

Cl₂ > F₂ > Br₂ > I₂

D

Br₂ > I₂ > F₂ > Cl₂

25

Lower members of alkenes form oily products on treatment with chlorine or bromine, so they are also known as?

A

Paraffins

B

Olefins

C

Acetylenes

D

Saturated hydrocarbons

26

Dehydration of alcohols to form alkenes is easiest for which type of alcohol?

A

Primary alcohol

B

Secondary alcohol

C

Tertiary alcohol

D

Methyl alcohol

27

The catalyst used for partial hydrogenation of an alkyne to a cis-alkene is?

A

Raney Nickel

B

Lindlar's catalyst

C

Platinum

D

Sodium in liquid NH₃

28

The addition of an unsymmetrical reagent to an unsymmetrical alkene is governed by?

A

Hund's Rule

B

Aufbau Principle

C

Markownikov's Rule

D

Pauli's Exclusion Principle

29

The test for detecting a double bond using bromine in CCl₄ results in?

A

Formation of a red precipitate

B

Discharge of the bromine colour

C

Formation of a silver mirror

D

Evolution of hydrogen gas

30

When an alkene reacts with cold, dilute, alkaline KMnO₄ solution (Baeyer's reagent), what is formed?

A

An epoxide

B

A vicinal glycol

C

An aldehyde

D

A ketone

31

The process where small organic molecules (monomers) combine to form larger molecules is known as?

A

Cracking

B

Isomerization

C

Polymerization

D

Hydrogenation

32

Mustard gas, a powerful vesicant used in World War I, is prepared from which starting material?

A

Methane

B

Ethyne

C

Ethene

D

Propane

33

The general molecular formula for alkynes is?

A

CₙH₂ₙ₊₂

B

CₙH₂ₙ

C

CₙH₂ₙ₋₂

D

CₙH₂ₙ₊₁

34

On an industrial scale, ethyne (acetylene) is prepared by the reaction of water with?

A

Calcium oxide

B

Calcium carbonate

C

Calcium carbide

D

Calcium hydroxide

35

The electrons in a triple bond of an alkyne are _______ exposed compared to the double bond of an alkene.

A

More

B

Equally

C

Less

D

Not

36

When water adds to ethyne in the presence of HgSO₄ and H₂SO₄, the initial unstable product is?

A

Acetaldehyde

B

Vinyl alcohol

C

Acetone

D

Ethanol

37

The polymerization of acetylene passed through a copper tube at 300°C produces?

A

Polyacetylene

B

Neoprene

C

Benzene

D

Divinyl acetylene

38

The hydrogen atom in terminal alkynes is slightly acidic due to which type of hybridization of the carbon atom?

A

sp³

B

sp²

C

sp

D

s

39

When ethyne reacts with an ammoniacal solution of silver nitrate, what is formed?

A

A black precipitate

B

A reddish-brown precipitate

C

A white precipitate

D

No reaction occurs

40

What is the general decreasing order of reactivity for aliphatic hydrocarbons?

A

Alkanes > Alkenes > Alkynes

B

Alkynes > Alkenes > Alkanes

C

Alkenes > Alkanes > Alkynes

D

Alkenes > Alkynes > Alkanes

41

In the Kolbe's electrolytic method for preparing alkanes, the hydrocarbon is formed at the?

A

Cathode

B

Anode

C

In the solution

D

At both electrodes

42

A π-bond is weaker than a σ-bond because the electrons are?

A

Tightly held between the nuclei

B

Less firmly held and away from the line joining the nuclei

C

Localized on one atom

D

Shared with hydrogen atoms

43

Ozonolysis of an alkene, followed by reduction with zinc and water, is used to?

A

Determine the number of carbon atoms

B

Locate the position of the double bond

C

Measure the heat of hydrogenation

D

Increase the chain length

44

Which compound is used as a general anaesthetic?

A

Methane

B

Propane

C

Ethene

D

Butane

45

The reaction of ethyne with HCN in the presence of a Cu₂Cl₂/NH₄Cl catalyst produces?

A

Methyl Nitrile

B

Acrylonitrile

C

Benzene

D

Ethanol

46

The catalyst used for converting an alkyne to a trans-alkene is?

A

Lindlar's catalyst

B

Raney Nickel

C

Palladium on BaSO₄

D

Na in liquid NH₃ at -33°C

47

Alkenes are weakly polar due to which hybridization?

A

sp

B

sp³

C

sp³d

D

sp²

48

In the halogenation of methane, which step involves the breaking of the Cl-Cl bond by UV light?

A

Propagation

B

Termination

C

Initiation

D

Oxidation

49

Which of the following is the formula for Neopentane?

A

CH₃CH(CH₃)CH₂CH₃

B

(CH₃)₄C

C

CH₃(CH₂)₃CH₃

D

(CH₃)₂CHCH(CH₃)₂