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Chemistry 1 Marks Question

Amines · CBSE STD 12 Science (CBSE - English Medium). 128 questions.

Questions · Page 3 of 3

1 Marks Question

Question 1011 Mark
Complete the following acid-base reaction and name the product:$\text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2+\text{HCl}\rightarrow$
Answer
$\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{NH}_2\rightarrow\text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_3 \ ^ +\text{Cl}^-\\\text{n-propylamine} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{n-propylammoniumchloride}$
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Question 1021 Mark
Complete the following reaction:$\text{C}_6\text{H}_5\text{N}_2\text{Cl}+\text{Br}_2(\text{aq})\rightarrow$
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Question 1031 Mark
Under what reaction conditions (acidic/ basic), the coupling reaction of aryldiazonium chloride with aniline is carried out?
Answer
The azo products obtained have an extended conjugate system having both the aromatic rings joined through the –N=N- bond. These compounds are often coloured and are used as dyes. Benzene diazonium chloride reacts with phenol in which the phenol molecule at its para position is coupled with the diazonium salt to form p-hydroxy azobenzene. This type of reaction is known as coupling reaction.
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Question 1041 Mark
The two strands in DNA are not identical but are complementary. Explain.
Answer
In the helical structure of DNA, the two strands are held together by hydrogen bonds between specific pairs of bases. Cytosine forms hydrogen bond with guanine, while adenine forms hydrogen bond with thymine. As a result, the two strands are complementary to each other.
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Question 1051 Mark
What is the difference between a nucleoside and a nucleotide?
Answer

A nucleoside is formed by the attachment of a base $to^{I'}$ position of sugar.
Nucleoside = Sugar + Base

On the other hand, all the three basic components of nucleic acids (i.e., pentose sugar, phosphoric acid, and base) are present in a nucleotide. Nucleotide = Sugar + Base + Phosphoric acid

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Question 1061 Mark
What is the role of pyridine in the acylation reaction of amines?
Answer
The products obtained by acylation reaction are known as amides. The reaction is carried out in the presence of a base stronger than the amine, like pyridine, which removes HCl so formed and shifts the equilibrium to the right-hand side.
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Question 1081 Mark
Mention two important uses of sulphanilic acid.
Answer
Sulphanilic acid is used in the manufacture of (i) dyes (ii) sulpha drugs.
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Question 1091 Mark
Account for the following:
Aniline gets coloured on standing in air for a long time.
Answer
Due to electron-donating effect (+R-effect) of $-NH_2$ group, the electron density on the benzene ring increases.
As a result, aniline is easily oxidised on standing in air for a long time to form coloured products.
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Question 1111 Mark
Why does acetylation of $-NH_2$ group of aniline reduce its activating effect?
Answer
The activating effect of $-NH_2$ group can be controlled by protecting the $-NH_2$ group by acetylation with acetic anhydride, then carrying out the desired substitution followed by hydrolysis of the substituted amide to the substituted amine. The lone part of electrons on nitrogen of acetanilide interacts with oxygen atom due to resonance as shown below:
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Question 1121 Mark
Complete the following acid-base reaction and name the product:$(\text{C}_2\text{H}_5)_3\text{N}+\text{HCl}\rightarrow$
Answer
$(\text{C}_2\text{H}_5)_3\text{N}+\text{HCl}\rightarrow\Big[(\text{C}_2\text{H}_5)_3\stackrel{{+}}{{\text{N}}}\text{H}\Big]\text{Cl}^-\\\text{Triethylamine} \ \ \ \ \ \ \ \ \text{Triemethylammonium chloride}$
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Question 1131 Mark
Complete the following reaction:$\text{C}_6\text{H}_5\text{NH}_2+\text{CHCl}_3+\text{alc.KOH}\rightarrow$
Answer
$\text{C}_6\text{H}_5\text{NH}_2+\text{CHCl}_3+\text{alc.KOH}\xrightarrow[]{\text{Carbyamine} \text{ reaction}}3\text{H}_2\text{O}+3\text{KCl}+\text{C}_6\text{H}_5-\text{NC}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Phynyl}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{isocynide}$
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Question 1141 Mark
What is the structure and IUPAC name of the compound, allyl amine?
Answer
$CH_2-CH-CH_2-NH_2,$ prop-2-en-1-amine.
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Question 1161 Mark
Arrange the following compounds in increasing order of dipole moment.
$CH_3CH_2CH_3, CH_3CH_2NH_2, CH_3CH_2OH.$
Answer
$CH_3CH_2CH_3 < CH_3CH_2NH_2 < CH_3CH_2OH$
Since, O is more electronegative than N, therefore, dipole moment of ethyl alcohol is higher than that of ethyl amine.
Propane however, has the least dipole moment since it is almost a non-polar molecule.
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Question 1171 Mark
Why is $NH_2$ group of aniline acetylated before carrying out nitration?
Answer
Direction nitration of aniline yields carry oxidation products in addition to the nitro derivatives. Moreover, in the strongly acidic medium, aniline is protonated to form the anilinium ion which is meta directing. That is why besides the ortho and para derivatives, significant amount of meta derivative is also formed.

However, by protecting the $-NH_2$ group by acetylation reaction with acetic anhydride, the nitration reaction can be controlled and the p-nitro derivative can be obtained as the major product.
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Question 1181 Mark
Why is benzene diazonium chloride not stored and is used immediately after its preparation?
Answer
Benzene diazonium chloride is very unstable. Therefore, it cannot be stored and is used immediately after its preparation.
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Question 1191 Mark
Mention the chief use of quaternary ammonium salts derived from long chain amines.
Answer
The quaternary ammonium salts derived from long chain aliphatic amines are used as detergents, such as,
${CH_3(CH_2)_{15}}^+N(CH^3)^3Br^–.$
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Question 1201 Mark
What is Hinsberg reagent?
Answer
Benzenesulphonyl chloride $(C_6H_5SO_2Cl)$, is also known as Hinsberg’s reagent. It reacts with primary and secondary amines to form sulphonamides. Secondary and tertiary amines can be distinguished by allowing them to react with Hinsberg’s reagent $($benzenesulphonyl chloride $C_6H_5SO_2Cl)$. Secondary amines react with Hinsberg’s reagent to form a product that is insoluble in an alkali. For example, N, N-diethylamine reacts with Hinsberg’s reagent to form N, N-diethylbenzenesulphonamide, which is insoluble in an alkali. Tertiary amines, however, do not react with Hinsberg’s reagent.
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Question 1211 Mark
For an amine $RNH_2,$ write the expression for $K_b$ to indicate its strength.
Answer
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \oplus\\\text{RNH}_2+\text{H}_2\text{O}\rightleftharpoons\text{RNH}_3+\text{OH}^-$$\text{K}_\text{b}=\frac{\ \ \oplus\\ [\text{RNH}_3][\text{OH}^-]}{\text{[RNH}_2]}$
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Question 1221 Mark
What is the best reagent to convert nitrile to primary amine?
Answer
Reduction of nitriles with sodium alcohol or $LiAlH_4$ gives primary amine.
$\text{R}-\text{CN}+4[\text{H}]\xrightarrow[\text{or LiAh}_4/\text{ether}]{\ \ \text{Na/C}_2\text{H}_5\text{OH}\ \ \ }\text{R}-\text{CH}_2\text{NH}_2\\\text{Alkyl nitrile}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Alkyl amine}(1^\circ)$
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Question 1231 Mark
Arrange the following compounds in the order of property indicated for each set:
p-toluidine, N, N-dimethyl-p-toluidine, p-nitroaniline, aniline (increasing basicity)
Answer
p-nitroaniline < aniline < p-toluidine < N, N-dimethyl-p-toluidine.
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Question 1261 Mark
A compound Z with molecular formula $C_3H_9N$ reacts with $C_6H_5SO_2Cl$ to give a solid, insoluble in alkali. Identify $Z$.
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Question 1271 Mark
What are enzymes?
Answer
Enzymes are proteins that catalyze biological reaction. They are very specific in nature and catalyze only a particular reaction for a particular substrate. Enzymes are usually named after a particular. For example, the enzyme used to catalyses the hydrolysis of maltose in glucose is named as maltase.$\text{C}_{12}\text{H}_{22}\text{O}_{11}\xrightarrow[]{\text{Maltase}}2\text{C}_6\text{H}_{12}\text{O}_6\\\text{maltose} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{glucose}$
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1 Marks Question - Page 3 - Chemistry STD 12 Science Questions - Vidyadip