chemistry MCQs - 12th class Chapter 07 Mcqs

1

The theory that organic compounds could only be manufactured within living things was known as?

A

Catenation Theory

B

Vital Force Theory

C

Hybridization Theory

D

Isomerism Theory

2

Who was the chemist that rejected the Vital Force Theory by synthesizing urea from an inorganic substance?

A

Berzelius

B

Lavoisier

C

Friedrick Wohler

D

Kolbe

3

Urea was synthesized from which inorganic compound?

A

Ammonium chloride

B

Ammonium nitrate

C

Ammonium carbonate

D

Ammonium cyanate

4

The self-linking property of carbon atoms to form long chains and rings is called?

A

Isomerism

B

Polymerization

C

Catenation

D

Hybridization

5

According to the modern definition, organic chemistry is the study of compounds of?

A

Carbon and oxygen

B

Silicon and hydrogen

C

Carbon and hydrogen (hydrocarbons) and their derivatives

D

Only living organisms

6

Most organic compounds are insoluble in water but dissolve readily in?

A

Polar solvents

B

Acids

C

Bases

D

Non-polar organic solvents

7

The reactions involving organic compounds are generally?

A

Fast and ionic

B

Instantaneous

C

Slow and molecular

D

Highly exothermic

8

Proteins are complex molecules with molecular masses ranging from a few thousands to?

A

Ten thousand

B

One hundred thousand

C

A million

D

A billion

9

Coal, petroleum, and natural gas are collectively known as?

A

Minerals

B

Organic sources

C

Fossil fuels

D

Hydrocarbons

10

Coal was formed from the remains of trees buried some _______ years ago.

A

100 million

B

200 million

C

500 million

D

1 billion

11

The initial stage of coal formation from wood due to bacterial and chemical reactions is?

A

Lignite

B

Bituminous

C

Anthracite

D

Peat

12

The process of heating coal in the absence of air at 500-1000°C is called?

A

Cracking

B

Reforming

C

Destructive distillation

D

Fractional distillation

13

The total estimated coal resources of Pakistan are about?

A

100 billion tonnes

B

184 billion tonnes

C

250 billion tonnes

D

500 billion tonnes

14

The major portion of natural gas is composed of which hydrocarbon?

A

Ethane

B

Propane

C

Butane

D

Methane

15

The blackish, liquid form of petroleum extracted from rocks is known as?

A

Refined oil

B

Gasoline

C

Crude oil

D

Kerosene

16

Which fraction of petroleum is used as a motor fuel?

A

Natural gas

B

Kerosene

C

Gas oil

D

Gasoline

17

The boiling point range for the Kerosene fraction is?

A

20-60 °C

B

60-100 °C

C

40-220 °C

D

175-325 °C

18

Fractional distillation of petroleum yields about what percentage of gasoline?

A

10%

B

20%

C

50%

D

75%

19

The process of breaking higher hydrocarbons into lower, more volatile hydrocarbons is called?

A

Reforming

B

Isomerism

C

Cracking

D

Polymerization

20

Which type of cracking uses a catalyst like silica (SiO₂) and alumina (Al₂O₃)?

A

Thermal Cracking

B

Steam Cracking

C

Catalytic Cracking

D

Hydrocracking

21

The quality of a fuel is indicated by its?

A

Boiling point

B

Calorific value

C

Octane number

D

Flash point

22

Which compound has been arbitrarily given an octane number of 100?

A

n-Octane

B

Benzene

C

2,2,4-trimethylpentane

D

n-Heptane

23

The process of converting straight-chain hydrocarbons into branched-chain ones is called?

A

Cracking

B

Reforming

C

Isomerization

D

Alkylation

24

Which additive was historically used to improve the octane number but causes air pollution?

A

Ethanol

B

Methanol

C

Tetraethyl lead (TEL)

D

MTBE

25

Organic compounds containing an open chain of carbon atoms are also called?

A

Alicyclic compounds

B

Aromatic compounds

C

Cyclic compounds

D

Aliphatic compounds

26

Compounds in which the ring consists of only carbon atoms are called?

A

Heterocyclic

B

Homocyclic

C

Acyclic

D

Inorganic

27

Which of the following is an example of an aromatic compound?

A

Cyclohexane

B

Pyridine

C

Benzene

D

Cyclopropane

28

A compound containing a heteroatom like nitrogen, oxygen, or sulfur in its ring is called?

A

Homocyclic

B

Carbocyclic

C

Alicyclic

D

Heterocyclic

29

Which of the following is a heterocyclic compound?

A

Naphthalene

B

Benzene

C

Anthracene

D

Pyridine

30

An atom or group of atoms that imparts specific properties to an organic compound is called a?

A

Functional group

B

Side chain

C

Homologous series

D

Isomer

31

The functional group -OH represents which class of compounds?

A

Ethers

B

Aldehydes

C

Alcohols

D

Ketones

32

The C=O functional group found within a carbon chain is characteristic of?

A

Aldehydes

B

Carboxylic acids

C

Esters

D

Ketones

33

What is the functional group for an ether?

A

Ether linkage (-O-)

B

Hydroxyl group (-OH)

C

Carbonyl group (C=O)

D

Amino group (-NH2)

34

The ground state electronic configuration of carbon is?

A

1s² 2s¹ 2p³

B

1s² 2s² 2p²

C

1s² 2s² 2p³

D

1s² 2s¹ 2p⁴

35

In sp³ hybridization, how many atomic orbitals are mixed?

A

One s and one p

B

One s and two p

C

One s and three p

D

One s and four p

36

The geometry associated with sp³ hybridization is?

A

Linear

B

Trigonal planar

C

Tetrahedral

D

Octahedral

37

The bond angle in a molecule with sp³ hybridization, like methane, is?

A

180°

B

120°

C

109.5°

D

90°

38

The structure of alkenes, like ethene, is explained by which mode of hybridization?

A

sp

B

sp²

C

sp³

D

dsp²

39

The bond angle between any two sp² hybrid orbitals is?

A

109.5°

B

180°

C

120°

D

90°

40

A carbon-carbon double bond consists of?

A

Two sigma bonds

B

Two pi bonds

C

One sigma and one pi bond

D

One sigma and two pi bonds

41

The structure of alkynes, like ethyne, is explained by which hybridization?

A

sp³

B

sp²

C

sp

D

dsp³

42

The geometry of a molecule with sp hybridization is?

A

Tetrahedral

B

Trigonal planar

C

Bent

D

Linear

43

A carbon-carbon triple bond consists of?

A

Three sigma bonds

B

Three pi bonds

C

One sigma and two pi bonds

D

Two sigma and one pi bond

44

Compounds having the same molecular formula but different structural formulas are called?

A

Isotopes

B

Allotropes

C

Isomers

D

Polymers

45

Which of the following alkanes is the simplest one to show structural isomerism?

A

Methane

B

Ethane

C

Propane

D

Butane

46

Isomerism that arises due to a difference in the nature of the carbon chain is called?

A

Position isomerism

B

Functional group isomerism

C

Chain isomerism

D

Metamerism

47

Dimethyl ether (CH₃-O-CH₃) and ethyl alcohol (CH₃-CH₂-OH) are examples of?

A

Chain isomers

B

Position isomers

C

Functional group isomers

D

Metamers

48

The type of isomerism that arises from the unequal distribution of carbon atoms on either side of a functional group is?

A

Tautomerism

B

Metamerism

C

Position isomerism

D

Chain isomerism

49

Cis-trans isomerism is also known as?

A

Optical isomerism

B

Structural isomerism

C

Geometric isomerism

D

Conformational isomerism

50

The necessary condition for cis-trans isomerism to arise is?

A

A single bond

B

A triple bond

C

Restricted rotation around a double bond

D

Free rotation around a single bond