Hydrocarbons Test

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Hydrocarbons Test - 51

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Weekly Quiz Competition

Question 1
1 / -0

What should be the correct IUPAC name for diethyl bromomethane?

A
1-Bromo-1, 1-diethylmethane

B
3-Bromopentane

C
3-Bromopentane

D
1-Bromopentane

Solution

The correct IUPAC name for diethylbromomethane is $$3 - Bromopentane.$$ It has molecular formula $$C_5H_{11}Br. $$
Question 2
1 / -0

An alkene on ozonolysis gives methanol as one of the product. Its structure is:

A

B

C

D

Solution
Question 3
1 / -0

Correct IUPAC name for the above compound is

A
2- ethyl-3-methylpentane

B
3,4- dimethyl hexane

C
2-sec-butylbutane

D
2, 3-dimethylbutane

Solution

In longest continuous chain both ethyl groups are included and $$3^{rd}$$ and $$4^{th}$$ carbon have methyl groups present as a substituent.
Question 4
1 / -0

Arrange the following in decreasing order of their boiling points:
(1) n-butane
(2) $$2$$-methyl butane
(3) n-pentane
(4) $$2,2$$-dimethyl propane

A
1>2>3>4

B
2>3>4>1

C
4>3>2>1

D
3>2>4>1

Solution

Boiling point is directly proportional to molar mass and surface area . It decreases on branching because surface area decreases. Hence , n-pentane has the highest and n-butane has the lowest boiling points and in rest two branching is there , therefore $$2$$-methyl butane has higher boiling point than $$2,2$$-dimethylpropane.

Hence, Option "D" is the correct answer.
Question 5
1 / -0

Which of the following is Non Aromatic?

A

B

C

D

Solution

$$\bf{Correct\ option-}$$ $$C$$

$$\bf{Explanation\ for\ correct\ option-}$$

Non-aromatic compounds are non-cyclic, non-planar, and do not hold a comprehensive conjugated $$\pi$$ system inside the ring.
Huckel's rule for Anti-aromatic compounds:
Number of $$\pi-$$ electrons $$=4n$$, where $$n=0,1,2,....$$

In option $$C$$, the total number of $$\pi$$ electrons are $$8$$. Hence, it follows the $$4n$$ rule of anti-aromaticity.

$$\bf{Explanation\ for\ incorrect\ options-}$$

Huckel's rule for Aromatic compounds:
Number of $$|pi-$$ electrons $$= (4n+2)$$, where $$n=0,1,2,....$$

In option $$A, B$$ and $$D$$, total number of $$\pi-$$ electrons are $$2,6,$$ and $$14$$. Hence these structures follow the $$(4n+2)$$ rule of aromaticity.
Question 6
1 / -0

The compound with the highest boiling point is

A
n-hexane

B
n-pentane

C
2, 2-dimethylpropane

D
2-methylbutane
Question 7
1 / -0

The correct IUPAC name of the following compound is:

A
4 - methyl - 3 - ethylhexane

B
3 - Ethyl - 4 - methyl hexane

C
3, 4 - ethylmethylhexane

D
4 - ethyl - 3 - methylhexane

Solution

Rules for nomenclature:
i) Pick up the longest carbon chain.
ii) Start numbering from the nearest branch.
iii) In case two branches are at same distance from the terminal carbon, the branch having higher molecular weight is on priority.

In this case, the longest chain is with six carbons, the closest carbon with the branch is $$3^{rd}$$ carbon. The next carbon with branch is $$4^{th}$$ carbon.

Hence the the correct IUPAC name of the following compound is 3 - Ethyl - 4 - methyl hexane.

Hence, option B is correct.
Question 8
1 / -0

In the above reaction, 'A' is a carbide of $$3^{rd}$$ period element which forms amphoteric oxide. D can be converted into B by using:

A
$$Ni$$

B
$$Na/ether$$

C
$$Zn- Hg / HCl$$

D
$${ LiAlH }_{ 4 }$$

Solution

$$Al_4C_3+H_2O \rightarrow CH_4 \xrightarrow {O_2/Mo_2O_3/500^o} HCHO $$
A B D

Clemmensen reduction:
Aldehyde and ketone are reduced to alkanes in presence of $$Zn-Hg$$ and conc. $$HCl$$
$$HCHO \xrightarrow {Zn-Hg/HCl} CH_4$$

The hydrolysis of metal carbide A gives metal hydroxide and methane B.

Methane B on oxidation with $$Mo_2O_3$$ at $$500^0C$$ gives Formaldehyde D.

The carbonyl group in formaldehyde D can be reduced to the methylene group to obtain methane B by using zinc amalgam in conc HCl. This reaction is known as Clemmensen's reduction.

So, the correct option is 'C'.

Question 9

1 / -0

Match the following

List -I (Products)	List -II (Reactants-Reaction)
A) Methane	(1) Sabatier - Senderens reaction of propylene
B) Ethane	(2) Wurtz reaction of methyl iodide
C) Propane	(3) Decarboxylation of sodium acetate
D) Butane	(4) Sodium butanoate by Kolbes electrolysis

(5) Sodium propanoate by Kolbes electrolysis

The correct match is :

A-2 B-3 C-1 D-5

A-4 B-2 C-1 D-5

A-3 B-2 C-1 D-5

A-2 B-3 C-1 D-4

Solution

Wurtz reaction: $$RX+2Na+XR\rightarrow R-R+2NaX$$
Sabatier senderens reaction: $$C_nH_{2n}+ H_2 \rightarrow C_nH_{2n+2} + heat$$
Kolbe's electrolysis: $$2RCOOK+2H_2O\rightarrow R-R+2CO_2+2KOH+H_2$$
In decarboxylatioin of sodium acetate $$R-H$$ form as a product, In all other reaction $$R-R$$ forms as a product.
In Sodium propanoate by Kolbes electrolysis reaction occur at anode:
$$2C_2H_5COO^{\bullet}\rightarrow 2C_2H_5^{\bullet}+2CO_2$$
$$2C_2H_5^{\bullet} \rightarrow C_4H_{10}$$

Question 10
1 / -0

The addition reactions shown by alkenes are the examples of:

A
electrophilic addition reaction

B
nucleophilic addition reaction

C
free radical addition reaction

D
the formation of carbanion as an intermediate

Solution

Alkenes undergo electrophilic addition reactions.

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Hydrocarbons Test - 51

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Hydrocarbons Test - 51

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Question 1

1-Bromo-1, 1-diethylmethane

3-Bromopentane

3-Bromopentane

1-Bromopentane

Solution

Question 2

Solution

Question 3

2- ethyl-3-methylpentane

3,4- dimethyl hexane

2-sec-butylbutane

2, 3-dimethylbutane

Solution

Question 4

1>2>3>4

2>3>4>1

4>3>2>1

3>2>4>1

Solution

Question 5

Solution

Question 6

n-hexane

n-pentane

2, 2-dimethylpropane

2-methylbutane

Question 7

4 - methyl - 3 - ethylhexane

3 - Ethyl - 4 - methyl hexane

3, 4 - ethylmethylhexane

4 - ethyl - 3 - methylhexane

Solution

Question 8

$$Ni$$

$$Na/ether$$

$$Zn- Hg / HCl$$

$${ LiAlH }_{ 4 }$$

Solution

Question 9

A-2 B-3 C-1 D-5

A-4 B-2 C-1 D-5

A-3 B-2 C-1 D-5

A-2 B-3 C-1 D-4

Solution

Question 10

electrophilic addition reaction

nucleophilic addition reaction

free radical addition reaction

the formation of carbanion as an intermediate

Solution

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