Tag: hydrocarbons

Questions Related to hydrocarbons

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.