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Haloalkanes and Haloarenes

JEE Chemistry · 31 questions · Page 1 of 4 · Click an option or "Show Solution" to reveal answer

Q1
What is DDT among the following?
A Greenhouse gas
B A fertilizer
C Biodegradable pollutant
D Non–biodegradable pollutant
Correct Answer
Option D
Solution
DDTDDT

is a non-biodegradable pollutant.

Q2
Alkyl halides react with dialkyl copper reagents to give
A alkenes
B alkyl copper halides
C alkanes
D alkenyl halides
Correct Answer
Option C
Solution

In Corey House synthesis of alkanes alkyl halide react with lithium dialkyl cuprate

R′X+LiR2Cu⟶ R′−R+RCu+LiXR'X + Li{R_2}Cu\overset{\,}\longrightarrow R' - R + RCu + LiX
Q3
Alkyl halide is converted into alkyl isocyanide by reaction with
A KCN\mathrm{KCN}
B NH4CN\mathrm{NH}_4 \mathrm{CN}
C NaCN\mathrm{NaCN}
D AgCN\mathrm{AgCN}
Correct Answer
Option D
Solution

Covalent character of

AgCN\mathrm{AgCN}

.

Q4
The compound formed on heating chlorobenzene with chloral in the presence concentrated sulphuric acid is
A gammexene
B hexachloroethane
C Freon
D DDT
Correct Answer
Option D
Solution
DDTDDT

is prepared by heating chlorbenzene and chloral with concentrated sulphuric acid

Q5
The isomeric deuterated bromide with molecular formula C4H8DBr\mathrm{C_4H_8DBr} having two chiral carbon atoms is
A 2 - Bromo - 1 - deuterobutane
B 2 - Bromo - 1 - deutero - 2 - methylpropane
C 2 - Bromo - 3 - deuterobutane
D 2 - Bromo - 2 - deuterobutane
Correct Answer
Option C
Solution

The isomeric deuterated bromide with molecular formula C4H8DBr\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{DBr} having two chiral carbon atoms is 2-Bromo-3-deuterobutane

Q6
The products A and B in the following reactions, respectively are A⟷Ag−NO2CH3−CH2−CH2−Br→AgCNB\mathrm{A} \stackrel{\mathrm{Ag}-\mathrm{NO}_2}{\longleftrightarrow} \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{Br} \xrightarrow{\mathrm{AgCN}} \mathrm{B}
A CH3−CH2−CH2−ONO,CH3−CH2−CH2−CN\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{ONO}, \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CN}
B CH3−CH2−CH2−NO2,CH3−CH2−CH2−CN\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{NO}_2, \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CN}
C CH3−CH2−CH2−ONO,CH3−CH2−CH2−NC\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{ONO}, \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{NC}
D CH3−CH2−CH2−NO2,CH3−CH2−CH2−NC\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{NO}_2, \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{NC}
Correct Answer
Option D
Solution
CH3−CH2−CH2−NO2(A)⟶Ag−NO2CH3−CH2−CH2−Br⟶AgCNCH3−CH2−CH2−NC(B)\mathrm{\mathop {C{H_3} - C{H_2} - C{H_2} - N{O_2}}\limits_{(A)} \overset{{Ag - N{O_2}}}\longrightarrow C{H_3} - C{H_2} - C{H_2} - Br\overset{{AgCN}}\longrightarrow \mathop {C{H_3} - C{H_2} - C{H_2} - NC}\limits_{(B)}}
Q7
Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of
A insolubility
B instability
C inductive effect
D steric hindrance
Correct Answer
Option D
Solution

Due to steric hindrance tertiary alkyl halide do not react by

SN2{S_N}2

mechanism they react by

SN1{S_N}1

mechanism.

SN2{S_N}2

mechanism is followed in case of primary and secondary alkyl halides . The order is

CH2−X>CH3−CH2X>(CH3)2CH.X>(CH3)3C−XC{H_2} - X > C{H_3} - C{H_2}X > {\left( {C{H_3}} \right)_2}CH.X > {\left( {C{H_3}} \right)_3}C - X
Q8
The pair from the following pairs having both compounds with net non-zero dipole moment is
A cis-butene, trans-butene
B CH2_2Cl2_2, CHCl3_3
C Benzene, anisidine
D 1,4-Dichlorobenzene, 1,3-Dichlorobenzene
Correct Answer
Option B
Solution

The correct option from the pairs having both compounds with a net non-zero dipole moment is: Option A: cis-butene, trans-butene\text{cis-butene, trans-butene} cis-butene has a net dipole moment because the two alkyl groups are on the same side of the molecule, causing an imbalance in the distribution of electrons.

However, trans-butene is symmetric, so the dipole moments of the two alkyl groups cancel each other out, giving it a net dipole moment of zero.

Therefore, this pair does not have both compounds with a net non-zero dipole moment.

Option B: CH2Cl2,CHCl3\text{CH}_2\text{Cl}_2, \text{CHCl}_3 Both CH2Cl2\text{CH}_2\text{Cl}_2 (dichloromethane) and CHCl3\text{CHCl}_3 (chloroform) have a net non-zero dipole moment due to the difference in electronegativity between the hydrogen and chlorine atoms.

Hence, this pair has both compounds with a net non-zero dipole moment.

Option C: Benzene, Anisidine\text{Benzene, Anisidine} Benzene has a symmetrical structure, leading to a net zero dipole moment.

Anisidine, however, does have a net dipole moment due to the asymmetry in its structure.

Therefore, this pair does not have both compounds with a net non-zero dipole moment.

Option D: 1,4-Dichlorobenzene, 1,3-Dichlorobenzene\text{1,4-Dichlorobenzene, 1,3-Dichlorobenzene} 1,4-Dichlorobenzene\text{1,4-Dichlorobenzene} has a symmetrical structure, leading to a net zero dipole moment.

However, 1,3-Dichlorobenzene\text{1,3-Dichlorobenzene} has a non-zero dipole moment due to the asymmetry in its structure.

Therefore, this pair does not have both compounds with a net non-zero dipole moment.

Q9
Which one of the following alkenes when treated with HCl yields majorly an anti Markovnikov product?
A Cl – CH = CH2
B F3C – CH = CH2
C CH3O – CH = CH2
D H2N – CH = CH2
Correct Answer
Option B
Solution

Markovnikov rule says negative part of the reagent attacks on the carbon of the double bond which have less number of hydrogen atom.

So in Anti-Markovnikov rule negative part of the reagent attacks on the carbon of the double bond which have more number of hydrogen atom.

Q10
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Haloalkanes react with KCN to form alkyl cyanides as a main product while with AgCN\mathrm{AgCN} form isocyanide as the main product. Reason (R) : KCN\mathrm{KCN} and AgCN\mathrm{AgCN} both are highly ionic compounds. In the light of the above statements, choose the most appropriate answer from the options given below :
A (A) is correct but (R)(\mathbf{R}) is not correct
B Both (A) and (R) are correct and (R) is the correct explanation of (A)
C (A) is not correct but (R) is correct
D Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Correct Answer
Option A
Solution

R−X+KCN⟶R−CN+KXR−X+AgCN⟶R−NC+AgX\begin{aligned} & \mathrm{R}-\mathrm{X}+\mathrm{KCN} \longrightarrow \mathrm{R}-\mathrm{CN}+\mathrm{KX} \\\\ & \mathrm{R}-\mathrm{X}+\mathrm{AgCN} \longrightarrow \mathrm{R}-\mathrm{NC}+\mathrm{AgX}\end{aligned} KCN\mathrm{KCN} is ionic so it provides cyanide ions in solution and attacks from carbon side on alkyl halide.

But AgCN\mathrm{AgCN} is covalent it cannot form cyanide ion so it attacks from nitrogen side and isocyanide is formed predominantly. A\mathrm{A} is correct R\mathrm{R} is not correct.

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