IIT JEE & NEET Question Bank with Solution: Hydrocarbons: Chemistry

Q.1. In Wurtz reaction the reagent used is

A) Na

B) Na/liq.NH $blank subscript 3$

C) Na/dry ether

D) Na/dry alcohol

Explanation -

In Wurtz reaction Na in dry ether is used as reagent.

Q.2. Gasoline has composition

A) $straight C subscript 8 minus straight C subscript 12$

B) $C subscript 2 minus C subscript 5$

C) $C subscript 7 minus C subscript 9$

D) None of these

Explanation-

Gasoline has composition $straight C subscript 7 minus straight C subscript 9$

Q.3. Butane formed on heating $C subscript 2 H subscript 5 I$ with Na in presence of ether is contaminated with impurities of

A) $C subscript 2 H subscript 4$

B) $C subscript 3 H subscript 6$

C) $C H subscript 4$

D) None of these

Explanation-

$2 straight C subscript 2 straight H subscript 5 straight l plus 2 Na rightwards arrow with Wurts space reacion on top straight C subscript 2 straight H subscript 5 minus stack straight C subscript 2 straight H subscript 5 with Butane below plus 2 Nal$

Above reaction proceeds through free radical mechanism.

Sometimes the free radical undergoes disproportionation.

$2 degree straight C subscript 2 straight H subscript 5 rightwards arrow from blank to blank of straight C subscript 2 straight H subscript 4 plus straight C subscript 2 straight H subscript 6$

Q.4. A mixture of methane and steam when passed over nickel supported on alumina catalyst at 725 $degree$ C given

A) CH $blank subscript 3$ OH

B) CO $blank subscript 2$ and H $blank subscript 2$

C) CO and H $blank subscript 2$

D) None of these

Explanation-

$CH subscript 4 plus straight H subscript 2 straight O rightwards arrow from Al subscript 2 straight O subscript 3 to Ni of stack CH subscript 3 OH with Methanol below plus straight H subscript 2$

Q.5. Ethylbenzene with Br $blank subscript 2$ in the presence of FeBr $blank subscript 3$ gives

A) Phenylbromoethane

B) o-and p-Bromotoluene

C) o-and p-Bromoethylbenzene

D) Mixture of all these

Q.6. During ozonolysis of CH $blank subscript 2$ = CH $blank subscript 2$ if reduction is carried out by LiAIH $blank subscript 4$ the products formed are

A) HCHO

B) HCOOH

C) CH $blank subscript 3$ OH

D) CH $blank subscript 2$ OHCH $blank subscript 2$ OH

Explanation-

$CH subscript 2 equals CH 2 rightwards arrow with straight O subscript 3 on top table row blank straight O blank row divided by blank backslash row cell CH subscript 2 end cell blank cell CH subscript 2 end cell row vertical line blank vertical line row straight O minus straight O end table _______ with LiAlH subscript 4 below and straight H subscript 2 straight O on top blank with ↴ for CH subscript 3 OH plus CH subscript 3 OH of below and blank on top$

Is some strong reducing agent is applied during hydrolysis of ozonide then alcohol is obtained.

Q.7. In preparation of alkane from alcohol using Al $blank subscript 2$ O $blank subscript 3$ which is effective factor ?

A) Porosity of Al $blank subscript 2$ O $blank subscript 3$

B) Temperature

C) Concentration

D) Surface area of Al $blank subscript 2$ O $blank subscript 3$

Q.8. Which among the following is the strongest ortho-para directing group ?

A) -OH

B) -CI

C) -OCH $blank subscript 3$

D) -CH $blank subscript 3$

Explanation-

-OH is strongest among the given groups.

Q.9. In methanol solution , bromine reacts with ethylene to yield BrCH $blank subscript 2$ CH $blank subscript 2$ OCH $blank subscript 3$ in addition to 1,2 - Dibromoethane because

A) The intermediate carbocation may react with Br

blank to the power of minus

or CH

blank subscript 3

B) The methyl alcohol solvolates the bromine

C) The reaction follows Markownikov's rule

D) This is a free radical mechanism

Explanation-

$CH subscript 2 equals CH subscript 2 plus Br subscript 2 rightwards arrow with CH subscript 3 OH on top space to the power of plus CH subscript 2 minus CH subscript 2 Br plus Br to the power of minus Intermadiate space carbocation space may space react space Br to the power of minus space or space CH subscript 3 OH space to space gives space distinct space products. table row cell CH presuperscript plus subscript 2 end cell cell negative CH subscript 2 Br end cell cell rightwards arrow with CH subscript 3 OH on top end cell cell CH subscript 3 minus end cell cell straight O with plus below and vertical line with straight H on top on top end cell cell negative CH subscript 2 Br end cell row blank cell downwards arrow Br minus end cell blank blank blank blank row cell BrCH subscript 2 end cell cell negative CH subscript 2 Br end cell blank blank blank blank row blank blank blank blank blank blank end table table row cell table row blank row ↴ row cell negative straight H to the power of plus end cell end table end cell row cell CH subscript 3 OCH subscript 2 CH subscript 2 Br end cell row blank end table$ $CH subscript 2 equals CH subscript 2 plus Br subscript 2 rightwards arrow with CH subscript 3 OH on top space to the power of plus CH subscript 2 minus CH subscript 2 Br plus Br to the power of minus Intermadiate space carbocation space may space react space Br to the power of minus space or space CH subscript 3 OH space to space gives space distinct space products. table row cell CH presuperscript plus subscript 2 end cell cell negative CH subscript 2 Br end cell cell rightwards arrow with CH subscript 3 OH on top end cell cell CH subscript 3 minus end cell cell straight O with plus below and vertical line with straight H on top on top end cell cell negative CH subscript 2 Br end cell row blank cell downwards arrow Br minus end cell blank blank blank blank row cell BrCH subscript 2 end cell cell negative CH subscript 2 Br end cell blank blank blank blank row blank blank blank blank blank blank end table table row cell table row blank row ↴ row cell negative straight H to the power of plus end cell end table end cell row cell CH subscript 3 OCH subscript 2 CH subscript 2 Br end cell row blank end table$

Q.10. When ethyl alcohol is heated with conc. H $blank subscript 2$ SO $blank subscript 4$ at 443 K , ethylene is formed by

A) Intramolecular hydration

B) Intermolecular hydration

C) Intermolecular dehydration

D) Intramolecular dehydration

Explanation-

$CH subscript 3 minus CH subscript 2 equals OH rightwards arrow from 443 space straight K to straight H subscript 2 SO subscript 4 of space CH subscript 2 equals CH subscript 2 plus straight H subscript 2 straight O$

IIT JEE & NEET Question Bank with Solution

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Tuesday, August 17, 2021

Hydrocarbons: Chemistry

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