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Questions Related to chemistry

Chloroform on reduction with zinc and water gives:

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. acetylene

  2. ethylene

  3. ethane

  4. methane

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Correct Option: D
Explanation:
Methane is formed.
$Zn +  2{H} _{2}O \rightarrow 2[H] + Zn{(OH)} _{2} $ 
$CH{Cl} _{3} + 6[H] \rightarrow C{H} _{4} + 6HCl$

Which of the following reaction will give acetylene as a major product?

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. $2[CH _{3}] \underset {\triangle}{\xrightarrow {Ag}}$

  2. $H _{3}C - CH _{2} - Br\underset {KOH}{\xrightarrow {alc.}}$

  3. $\underset {\underset {Br}{|}}{CH _{2}} - \underset {\underset {Br}{|}}{CH _{2}} \underset {\triangle}{\xrightarrow {Zn}}$

  4. All of these

Show answer
Correct Option: A
Explanation:

Only $2[CH _3] \xrightarrow[\Delta]{Ag} HC \equiv CH$ give acetylene

$B)$ $H _3C - CH _2 - Br \xrightarrow[KOH]{ak} CH _2 = CH _2$
$C)$ $\underset{Br}{\underset{|}{CH _2}} - \underset{Br}{\underset{|}{CH _2}} \rightarrow H _2C = CH _2$

How many grams of hydrogen is required to saturate one mole of acetylene?

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. 3 g

  2. 6 g

  3. 10 g

  4. 4 g

Show answer
Correct Option: D
Explanation:

The hydrogenation of acetylene can be written as:
$C _{2}H _{2} + 2H _{2} \rightarrow C _{2}H _{6}$
As 2 moles of hydrogen are required to saturate one mole of acetylene and 1 mole = 2g of $H _{2}$, therefore 4g of hydrogen are required to saturate one mole of acetylene .

Ethene is obtained by dehydrobromination of:

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. CHBr = CHBr

  2. $CH _3CHBr _2$

  3. $CH _3 - CH _2Br$

  4. None of these

Show answer
Correct Option: C
Explanation:

Dehydrobromination is an organic reaction in which alkyl halide when boiled with alc.alkali gives corresponding alkene called as beta-elimination reaction.

Aniline and N-methylaniline can be distinguished by using the:
(A) Hoffman Mustard oil reaction
(B)  Hinsberg reagent
(C)  Carbylamine test
(D)   Mulliken Test

distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

  1. B and C

  2. C only

  3. A, B and C

  4. A, B, C and D

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Correct Option: A

Nitration of acetanilide followed by hydrolysis gives

distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

  1. Ortho nitro aniline

  2. Para nitroaniline

  3. Ortho and para nitroaniline

  4. Ortho nitro anilinium ion

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Correct Option: B

The reaction between primary amine, chloroform and few drops of alcoholic KOH is known as: 

distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

  1. Hofmann's reaction

  2. Reimer-Tiemann's reaction

  3. Carbylamine reaction

  4. Kolbe's reaction

Show answer
Correct Option: C
Explanation:
Carbylamine reaction:
$C{ H } _{ 3 }C{ H } _{ 2 }N{ H } _{ 2 }+CH{ Cl } _{ 3 }+3KOH\longrightarrow C{ H } _{ 3 }C{ H } _{ 2 }NC+3KCl+3{ H } _{ 2 }O$
It forms isocyanide.

Aniline and diphenylamine may be distinguished by:

distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

  1. lassaignes test

  2. schiffs test

  3. carbyl amine reaction

  4. solubility test

Show answer
Correct Option: C
Explanation:

Aniline and diphenylamine may be distinguished by carbylamine reaction.
Aniline is a primary amine and diphenylamine is a secondary amine.
carbylamine reaction is given by primary amines. It is not given by secondary or tertiary amines.
In Hoffmann's carbylamine test (also known as Isocyanide test), aliphatic or aromatic primary amine is heated with chloroform  in presence of alcoholic potassium hydroxide to give foul smelling alkyl/aryl  isocyanide or carbylamine.
$\underset {} {C _6H _5-NH _2} + CHCl _3  + 3KOH  \xrightarrow {heat} C _6H _5-NC  + 3KCl + 3H _2O$

Which of the following is an example of azo dye?

distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

  1. Orange-1

  2. Malachite green

  3. Indigo

  4. Martius yellow

Show answer
Correct Option: A
Explanation:

Azo dye are a large class of synthetic organic dyes, that contain nitrogen as the azo group or $−N=N−$ as a part of their molecular structures. Orange-1 is an example of azo dye.

Primary, secondary, tertiary amines can be separated by the following except: 

distinction between pairs of amines organic compounds containing nitrogen organic compounds with functional group containing nitrogen chemistry

  1. Fractional distillation

  2. Fractional method using diethyl oxalate

  3. Hinsberg's method using $\displaystyle { C } _{ 6 }{ H } _{ 5 }{ SO } _{ 2 }Cl$

  4. Selective crystallisation

Show answer
Correct Option: D
Explanation:

Separation of $1^o,\, 2^o$ and $3^o$ amines:

$1^o,\, 2^o$ and $3^o$ amines + $R _4NX \xrightarrow{distillation}$ Mixture of $1^o,\, 2^o,\, 3^o$ amine
Mixture  of $1^o,\, 2^o,\, 3^o$ amine can be separated by following methods.
(i) Fractional distillation: The mixture of amines may be fractional distillation because their boiling points are quite different. It is used in industry.

(ii) Hinsberg method: In this method mixture of amines is seperated by using benzene sulphonyl chloride (Hinsberg's reagent).
$C _6H _5SO _2Cl+1^o\,amine \to Product \xrightarrow{KOH} dissolve$
$C _6H _5SO _2Cl+2^o\,amine \to Product \xrightarrow{KOH} insoluble$
$3^o$ amine does not react with benzene sulphonyl chloride.

(iii) Hofman method: In this method mixture of amines is separated by using ethyl oxalate.
$1^o$ amine + ethyl oxalate $\to$ solid product
$2^o$ amine + ethyl oxalate $\to$ liquid product
$3^o$ amine + ethyl oxalate $\to$ No reaction