chemistry MCQs - 12th class Chapter 10 Mcqs

1

Halogen derivatives of alkanes are also called __________.

A

Alkenes

B

Alkynes

C

Haloalkanes

D

Arenes

2

In a primary alkyl halide, the halogen atom is attached to a carbon which is further attached to how many carbon atoms?

A

Two

B

Three

C

One or no

D

Four

3

The general formula for monohaloalkanes or alkyl halides is __________.

A

R-OH

B

R-X

C

R-O-R

D

R-CHO

4

Which of the following is an example of a secondary alkyl halide?

A

Chloromethane

B

2-Chloropropane

C

2-Chloro-2-methylpropane

D

1-Chloropropane

5

2-Chloro-2-methylpropane is an example of a __________ alkyl halide.

A

Primary

B

Secondary

C

Tertiary

D

Quaternary

6

According to IUPAC rules, the first step in naming an alkyl halide is to select the __________.

A

Shortest carbon chain

B

Carbon chain with most branches

C

Longest continuous carbon chain

D

Carbon chain forming a ring

7

While numbering the carbon chain, the carbon atom bearing the halogen gets the __________.

A

Highest possible number

B

Middle number

C

Lowest possible number

D

An even number

8

The common name for CH3-CH2-Br is __________.

A

Methyl bromide

B

Bromoethane

C

Ethyl bromide

D

Propyl bromide

9

What is the IUPAC name for Isobutyl chloride?

A

1-Chloro-2-methylpropane

B

2-Chlorobutane

C

1-Chlorobutane

D

2-Chloro-2-methylpropane

10

The best method for the preparation of alkyl halides is from __________.

A

Alkanes

B

Alkenes

C

Alcohols

D

Ethers

11

What catalyst is used in the reaction of alcohols with halogen acids (HX)?

A

H2SO4

B

NaOH

C

ZnCl2

D

Pyridine

12

When preparing alkyl chlorides from alcohols using thionyl chloride (SOCl2), what is the solvent used?

A

Water

B

Ether

C

Pyridine

D

Acetone

13

The reaction of alkyl chloride with sodium iodide (NaI) is an excellent method for preparing __________.

A

Alkyl fluoride

B

Alkyl bromide

C

Alkyl iodide

D

Alkyl astatide

14

Which factor is the main determinant of the reactivity of alkyl halides?

A

Bond polarity

B

Bond energy

C

Size of alkyl group

D

Electronegativity of carbon

15

Which carbon-halogen bond is the weakest?

A

C-F

B

C-Cl

C

C-Br

D

C-I

16

What is the correct order of reactivity for alkyl halides?

A

R-F > R-Cl > R-Br > R-I

B

R-I > R-Br > R-Cl > R-F

C

R-Cl > R-F > R-I > R-Br

D

R-Br > R-I > R-Cl > R-F

17

The carbon atom in an alkyl halide bonded to the halogen has a __________.

A

Partial positive charge

B

Partial negative charge

C

Neutral charge

D

Full positive charge

18

A species that is 'nucleus loving' and has an unshared electron pair is called a(n) __________.

A

Electrophile

B

Carbocation

C

Free radical

D

Nucleophile

19

Which of the following is a neutral nucleophile?

A

OH-

B

CN-

C

Br-

D

H2O

20

In a nucleophilic substitution reaction, the group that departs with an unshared pair of electrons is called the __________.

A

Attacking group

B

Substrate

C

Leaving group

D

Solvent

21

Which of the following is considered a good leaving group?

A

OH-

B

OR-

C

NH2-

D

Br-

22

Nucleophilic substitution reactions that occur in a single step are designated as __________.

A

SN1

B

SN2

C

E1

D

E2

23

The SN2 mechanism involves a __________ step reaction.

A

Single

B

Two

C

Three

D

Four

24

What is the molecularity of an SN2 reaction?

A

0

B

1

C

2

D

3

25

During an SN2 reaction, the configuration of the alkyl halide molecule gets __________.

A

Inverted

B

Retained

C

Racemized

D

Unchanged

26

Primary alkyl halides, when attacked by nucleophiles, always follow the __________ mechanism.

A

SN1

B

SN2

C

E1

D

E2

27

Nucleophilic substitution reactions that involve two steps and form a carbocation intermediate are designated as __________.

A

SN1

B

SN2

C

E1

D

E2

28

The first step in an SN1 mechanism is the __________.

A

Attack of the nucleophile

B

Formation of a transition state

C

Ionization of the alkyl halide

D

Departure of the leaving group and nucleophile attack simultaneously

29

The rate-determining step in an SN1 reaction depends on the concentration of the __________.

A

Nucleophile only

B

Alkyl halide only

C

Both alkyl halide and nucleophile

D

Solvent

30

Tertiary alkyl halides, when attacked by a nucleophile, always follow the __________ mechanism.

A

SN1

B

SN2

C

E1

D

E2

31

An SN1 reaction results in __________.

A

100% inversion of configuration

B

100% retention of configuration

C

50% inversion and 50% retention

D

No change in configuration

32

Reactions that involve the removal of HX are called __________ reactions.

A

Substitution

B

Addition

C

Elimination

D

Rearrangement

33

The hydrogen atom attached to the beta-carbon of an alkyl halide is attacked by a base in __________ reactions.

A

Substitution

B

Elimination

C

Addition

D

Hydrolysis

34

Primary alkyl halides generally follow the __________ elimination mechanism.

A

E1

B

E2

C

Both E1 and E2

D

Neither E1 nor E2

35

The rate of an E1 reaction depends on the concentration of the __________.

A

Base only

B

Alkyl halide only

C

Both alkyl halide and base

D

Product

36

Wurtz synthesis is used for the preparation of symmetrical __________.

A

Alcohols

B

Ethers

C

Alkyl halides

D

Alkanes

37

Alkyl halides can be reduced to alkanes using zinc in the presence of an acid like __________.

A

H2SO4

B

HNO3

C

CH3COOH

D

H3PO4

38

Reaction of methyl chloride with sodium lead alloy gives __________.

A

Tetraethyl lead

B

Triethyl lead

C

Tetramethyl lead

D

Dimethyl lead

39

Grignard reagents are organo-metallic compounds with the general formula __________.

A

R-X

B

R-Na

C

R-Li

D

R-Mg-X

40

The solvent used for the preparation of a Grignard reagent must be __________.

A

Aqueous

B

Acidic

C

Moisture-free

D

Basic

41

What is the order of reactivity of alkyl halides with magnesium for Grignard reagent formation?

A

Alkyl iodide > Alkyl bromide > Alkyl chloride

B

Alkyl chloride > Alkyl bromide > Alkyl iodide

C

Alkyl fluoride > Alkyl chloride > Alkyl bromide

D

Alkyl bromide > Alkyl chloride > Alkyl iodide

42

The C-Mg bond in a Grignard reagent is highly __________.

A

Non-polar

B

Ionic

C

Polar

D

Stable

43

The alkyl carbon in a Grignard reagent has a partial __________ charge.

A

Positive

B

Negative

C

Neutral

D

No

44

Reaction of Grignard reagent with water produces an __________.

A

Alcohol

B

Ether

C

Alkane

D

Aldehyde

45

When CO2 reacts with ethyl magnesium bromide followed by hydrolysis, the product is __________.

A

Acetic acid

B

Formic acid

C

Propanoic acid

D

Butanoic acid

46

The reaction of a Grignard reagent with formaldehyde (HCHO) produces a __________ alcohol.

A

Primary

B

Secondary

C

Tertiary

D

Quaternary

47

A secondary alcohol is formed when a Grignard reagent reacts with __________.

A

Formaldehyde

B

Any other aldehyde (e.g., CH3CHO)

C

A ketone

D

Carbon dioxide

48

The reaction between a Grignard reagent and a ketone (like acetone) yields a __________ alcohol.

A

Primary

B

Secondary

C

Tertiary

D

Phenol

49

Which of the following is NOT a nucleophile according to the PDF?

A

H2S

B

NH3

C

BF3

D

CN-

50

The molecularity of E2 reactions is always __________.

A

One

B

Two

C

Three

D

Zero