Amines Test

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Amines Test - 21

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Weekly Quiz Competition

Question 1
1 / -0

Amines are almost colourless but develop colour on keeping in the air for a long time, because:

A
they are readily oxidised in air to form coloured oxidation product.

B
they react with oxygen present in air in very less amount.

C
they regain color in presence of air.

D
none of these

Solution

(1). Amines are basic compound.
(2) They are colourless but develop colour on keeping in the air for a long time because they react readily air and get oxidised.
Question 2
1 / -0

The boiling point of amines are higher than that of hydrocarbon because:

A
they form inter molecular H-bonds

B
they are polar

C
they form ionic bonds

D
both A and B

Solution

Amines have higher boiling points than hydrocarbons, as C-N bond in amines is more polar than a C-C bond in hydrocarbons.
Due to the polar nature of amines it forms intermolecular H-bonds and exists as associated molecules.
Thus, its boiling point is higher than that of hydrocarbons.
Question 3
1 / -0

Which one of the amine have highest boiling point?

A
Primary amine

B
Secondary amine

C
Tertiary amine

D
all of these

Solution

Primary amines have higest boiling point because of 2 hydrogen atom, more hydrogen bonding occur.
Question 4
1 / -0

Reduction of aryl nitriles in presence of $LiAlH_4$ Gives :

A
Aryl nitro compounds

B
Aryl amines

C
Aryl iso cyanides

D
Alky amines

Solution

Reduction of aryl nitriles in presence of $LiAlH_4$ Gives Aryl Amines. Alkyl and aryl cyanides (nitriles) can be reduce by $LiAlH_4$ ) or catalytic hydrogenation
Hence option B is correct.
Question 5
1 / -0

Which of the following is true?

A
Aliphatic amines are stronger bases than ammonia.

B
Aliphatic amines are weaker bases than ammonia.

C
Aliphatic amines ammonia have approximately same basic strength.

D
Low molecular weight aliphatic amines are stronger bases than ammonia.

Solution

Aliphatic amines are stronger bases than ammonia due $+I$ (electron releasing) effect of alkyl groups. The electron density on N increases and lone pair of electrons can be easily donated.
Question 6
1 / -0

Based on the concept of the hydration of protonated amines, which of the following represents correct order of decreasing basic strength of amines?

A
primary amine $>$ secondary amine $>$ tertiary amine

B
tertiary amine $>$ primary amine $>$ secondary amine

C
tertiary amine $>$ secondary amine $>$ primary amine

D
primary amine $>$ tertiary amine $>$ secondary amine

Solution

Based on the concept of the hydration of protonated amines, the following represents the correct order of decreasing basic strength of amines
primary amine $>$ secondary amine $>$ tertiary amine
This is the same order in which the degree of hydrogen bond formation, the extent of hydration and the stabilisation of protonated amines decrease.
Question 7
1 / -0

$C_6H_5CN + H_2/Ni \rightarrow$ ?

A
$C_6H_5-CH_2-CH_2-NH_2$

B
$C_6H_5-CH_2-NH_2$

C
$C_6H_6-CH_2-NH_2$

D
$C_6H_5-NH_2$

Solution

Reduction of cyanide occur to $1^0$ amine in presence of $H_2/Ni$ as reducing agent.
Question 8
1 / -0

Which of the following is true?

A
Greater the K $_b$ value, the stronger is the base. The smaller the value of pK $_b$ , more is the basic strength of amine.

B
Greater the K $_b$ value, the weaker is the base. The smaller the value of pK $_b$ , less is the basic strength of amine.

C
Greater the K $_b$ value, the weaker is the base. The smaller the value of pK $_b$ , more is the basic strength of amine.

D
Greater the K $_b$ value, the stronger is the base. The smaller the value of pK $_b$ , less is the basic strength of amine.

Solution

Greater the K $_b$ value, the stronger is the base. The smaller the value of pK $_b$ , more is the basic strength of amine.
When the K $_b$ value is greater (pK $_b$ )
value is smaller, the extent of dissociation is greater. the hydroxide concentration is greater and stronger is the base.
Question 9
1 / -0

Identify the highest soluble amine from the following.

A
Primary amine

B
Secondary amine.

C
Tertiary amine

D
None of these

Solution

The highest soluble amine would be primary amine, because it can form more H-bonds with water since $1^o$ amine have $-NH_2$ (2 Hydrogen) for H-bonding which decreases as we move on to secondary or tertiary amine.
Question 10
1 / -0

Aromatic amines are insoluble in water because:

A
Due to the larger hydrocarbon part which tends to retard the formation of H-bonds.

B
Due to the larger hydrocarbon part which tends to retard the formation of H-Nbonds.

C
Due to the larger hydrocarbon part which tends to retard the formation of H-Cbonds.

D
none of these

Solution

Aromatic amines are insoluble in water because of large hydrocarbon part (hydrophobic) part which retards the formation of H-bonding.

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Amines Test - 21

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Amines Test - 21

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Question 1

they are readily oxidised in air to form coloured oxidation product.

they react with oxygen present in air in very less amount.

they regain color in presence of air.

none of these

Solution

Question 2

they form inter molecular H-bonds

they are polar

they form ionic bonds

both A and B

Solution

Question 3

Primary amine

Secondary amine

Tertiary amine

all of these

Solution

Question 4

Aryl nitro compounds

Aryl amines

Aryl iso cyanides

Alky amines

Solution

Question 5

Aliphatic amines are stronger bases than ammonia.

Aliphatic amines are weaker bases than ammonia.

Aliphatic amines ammonia have approximately same basic strength.

Low molecular weight aliphatic amines are stronger bases than ammonia.

Solution

Question 6

primary amine >>> secondary amine >>> tertiary amine

tertiary amine >>> primary amine >>> secondary amine

tertiary amine >>> secondary amine >>> primary amine

primary amine >>> tertiary amine >>> secondary amine

Solution

Question 7

C6H5−CH2−CH2−NH2C_6H_5-CH_2-CH_2-NH_2C6​H5​−CH2​−CH2​−NH2​

C6H5−CH2−NH2C_6H_5-CH_2-NH_2C6​H5​−CH2​−NH2​

C6H6−CH2−NH2C_6H_6-CH_2-NH_2C6​H6​−CH2​−NH2​

C6H5−NH2C_6H_5-NH_2C6​H5​−NH2​

Solution

Question 8

Greater the Kb_bb​ value, the stronger is the base. The smaller the value of pKb_bb​, more is the basic strength of amine.

Greater the Kb_bb​ value, the weaker is the base. The smaller the value of pKb_bb​, less is the basic strength of amine.

Greater the Kb_bb​ value, the weaker is the base. The smaller the value of pKb_bb​, more is the basic strength of amine.

Greater the Kb_bb​ value, the stronger is the base. The smaller the value of pKb_bb​, less is the basic strength of amine.

Solution

Question 9

Primary amine

Secondary amine.

Tertiary amine

None of these

Solution

Question 10

Due to the larger hydrocarbon part which tends to retard the formation of H-bonds.

Due to the larger hydrocarbon part which tends to retard the formation of H-Nbonds.

Due to the larger hydrocarbon part which tends to retard the formation of H-Cbonds.

none of these

Solution

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primary amine $>$ secondary amine $>$ tertiary amine

tertiary amine $>$ primary amine $>$ secondary amine

tertiary amine $>$ secondary amine $>$ primary amine

primary amine $>$ tertiary amine $>$ secondary amine

$C_6H_5-CH_2-CH_2-NH_2$

$C_6H_5-CH_2-NH_2$

$C_6H_6-CH_2-NH_2$

$C_6H_5-NH_2$

Greater the K $_b$ value, the stronger is the base. The smaller the value of pK $_b$ , more is the basic strength of amine.

Greater the K $_b$ value, the weaker is the base. The smaller the value of pK $_b$ , less is the basic strength of amine.

Greater the K $_b$ value, the weaker is the base. The smaller the value of pK $_b$ , more is the basic strength of amine.

Greater the K $_b$ value, the stronger is the base. The smaller the value of pK $_b$ , less is the basic strength of amine.