Tag: acetylene

Questions Related to acetylene

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

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

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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

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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

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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.