Tag: hydrocarbons

Questions Related to hydrocarbons

Acetylene may be prepared using Kolbes electrolytic method employing:

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. Pot. acetate

  2. Pot. succinate

  3. Pot. fumarate

  4. None of these

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Correct Option: C
Explanation:

Acetylene may be prepared using Kolbes electrolytic method employing potassium fumerate. Acetylene is obtained at anode. The solution is basic due to formation of KOH at cathode.
$\displaystyle  (CHCOONa) _2 \xrightarrow {Electrolysis} C _2H _2+2CO _2+2KOH + H _2$

$C _{2}H _{2}$ on reaction with Na followed by reaction with $C _{2}H _{5}I$ gives 'X'. The molecular formula of 'X' is:

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. $C _{2}H _{6}$

  2. $C _{4}H _{8}$

  3. $C _{4}H _{6}$

  4. $C _{3}H _{6}$

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Correct Option: C
Explanation:

Reaction: $CH \equiv CH \xrightarrow{Na} Na - C \equiv  CH \xrightarrow{C _2H _5I} C _2H _5 - C \equiv  CH + NaI$


Hence, the correct option is $C$

1, 1, 2, 2-Tetra bromoethane $\xrightarrow {Zn}A$ $\xrightarrow{red hot \ tube}B$,


 Then B is:

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. Acetylene

  2. Ethylene

  3. Ethane

  4. Benzene

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Correct Option: D
Explanation:

$H-\overset{Br}{\overset{|}{\underset{Br}{\underset{|}{C}}}}-\overset{Br}{\overset{|}{\underset{Br}{\underset{|}{C}}}}-H\xrightarrow[\triangle]{2n}H-C\underset{(A)}{\equiv} C-H\xrightarrow{ red hot \ tube} C _6H _6$


Option D is correct.

$H-C\equiv C-H+NaNH _{2}\longrightarrow A\overset{2 \ mole \ CH _3I}{\longrightarrow}B$


Then B is :

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. 1-Butyne

  2. 2-Butyne

  3. 2-Pentyne

  4. Propyne

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Correct Option: B
Explanation:

Reaction of process:
$CH\equiv CH+2NaNH _2\rightarrow NaC\equiv CNa\xrightarrow {2 mole CH _3I} CH _3CH\equiv CHCH _3$


Option B is correct.

$X+2Zn\overset{Alcohol}{\rightarrow}H-C\equiv C-H$ 


Here X is :

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. 1, 1-Dibromoethane

  2. 1, 2-Dibromoethane

  3. Dibromo ethane

  4. 1, 1, 2, 2-Tetrachloroethane

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Correct Option: D
Explanation:

This is dehalogenation process:


$CHCl _2-CHCl _2+2Zn\overset{Alcohol}{\longrightarrow}H-C\equiv C-H$

Option D is correct.

Kolbes electrolytic method can be applied on?

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. $CH _{3}-CH _{3}-COOK$

  2. $CH _2-COOK$

     $|$
    $CH _2-COOK$

  3. $CH _2-CH _3$

     $|$
    $CH _2-COOK$

  4. $CH _2-COONa$

     $|$
    $CH _2-COONa$

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Correct Option: A,B,D

What is the by-product formed when calcium carbide reacts with cold water?   

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. Calcium hydroxide

  2. Calcium oxide

  3. Carbon dioxide

  4. Calcium hydride

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Correct Option: A
Explanation:

When carbide reacts with cold water, the by-product formed is calcium hydroxide.

Calcium carbide reacts with water to produce :

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. ethane

  2. ether

  3. acetylene

  4. alcohol

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Correct Option: C
Explanation:

The chemical reaction can be shows as follows which indicates the formation of acetylene
$CaC _2(s) + 2H _2O(l) \rightarrow C _2 H _2(g) + Ca(OH) _2 (g)$

Which of the following is used for the production of oxy-acetylene flame for welding and cutting metals?

chemistry hydrocarbons introduction to alkenes - ethyne acetylene alkynes

  1. Ethane

  2. Ethene

  3. Ethyne

  4. None of the above

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Correct Option: C
Explanation:

Ethyne is used for the production of oxy-acetylene flame for welding and cutting metals.

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} $ 
$CH{Cl} _{3} + 6[H] \rightarrow C{H} _{4} + 6HCl$