Question 1

In the dichlorination reaction of propane, mixture of products are obtained. How many isomers, the mixture contains…………

Accepted Answer

The dichlorination of propane can lead to four different isomers: 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, and 2,2-dichloropropane.

Question 2

Which of the following cycloalkane gives open chain compound, when reacts with bromine………..

Accepted Answer

Cyclopropane reacts with bromine to give an open chain compound due to the ring strain in cyclopropane, which makes it more reactive and prone to ring opening reactions.

Question 3

Grignard reagent is not prepared in aqueous medium but prepared; in ether medium because the reagent…………..

Accepted Answer

Grignard reagents react with water, which would destroy the reagent, so they are prepared in an ether medium to prevent this reaction.

Question 4

A sample of petrol is a mixture of 30% n-heptane and 70% iso-octane. The sample has octane number…………

Accepted Answer

The octane number of a fuel is a measure of its resistance to knocking or pinging during combustion, typically in a spark-ignition internal combustion engine. n-Heptane has an octane number of 0, indicating it knocks easily, while iso-octane has an octane number of 100, indicating high resistance to knocking. The sample's octane number is calculated based on the percentage of each component and their respective octane numbers. Thus, for a mixture of 30% n-heptane (octane number = 0) and 70% iso-octane (octane number = 100), the octane number is (0.30*0) + (0.70*100) = 70.

Question 5

Photochemical chlorination of alkane is initiated by a process of……………

Accepted Answer

Photochemical chlorination of alkane is initiated by homolysis, where the chlorine molecule absorbs light and splits into two chlorine radicals, starting the chain reaction of substitution.

Question 6

A petroleum fraction having boiling range 70-200°C and containing 6-10 carbon atoms per molecule is called………..

Accepted Answer

Gasoline is the petroleum fraction that typically has a boiling range of about 70-200°C and contains molecules with 6 to 10 carbon atoms, making it suitable for use as a fuel in internal combustion engines.

Question 7

Pick out the alkane which differs from the other members of the group.

Accepted Answer

2,2-dimethyl butane is the only alkane with a different number of carbon atoms (6) compared to the others, which all have 5 carbon atoms.

Question 8

2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly……..

Accepted Answer

In the presence of sunlight, bromination of alkanes occurs via a radical halogenation mechanism. 2-Methylbutane will primarily form 2-bromo-2-methylbutane because the tertiary hydrogen (the one on the carbon bonded to three other carbons) is the most susceptible to radical substitution, leading to the most stable tertiary radical intermediate.

Question 9

Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is…………..

Accepted Answer

2,3-dimethylbutane has two types of hydrogen atoms that can be replaced by chlorine, leading to two different monochlorinated products.

Question 10

Which group is present on alcohol.

Accepted Answer

The OH (hydroxyl) group is present on alcohols, characterizing them by the presence of one or more hydroxyl groups attached to a carbon atom.

Question 11

Which suffix attached in alcohol.

Accepted Answer

The suffix "-ol" is used in organic chemistry to denote substances that are alcohols.

Question 12

Butane-2-ol is …….

Accepted Answer

Butane-2-ol is a secondary alcohol because the hydroxyl (-OH) group is attached to a carbon atom that is connected to two other carbon atoms.

Question 13

Pentanol is a……..

Accepted Answer

The answer of Pentanol is a……..
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Question 14

Glycerol is a……

Accepted Answer

Glycerol is a trihydric alcohol because it contains three hydroxyl (-OH) groups.

Question 15

Which is primary alcohol…….

Accepted Answer

Butane-1-ol is a primary alcohol because the hydroxyl group (-OH) is attached to a carbon atom that is only connected to one other carbon atom, which is the definition of a primary alcohol.

Question 16

General formula of primary alcohol is …….

Accepted Answer

The general formula for a primary alcohol is RCH2OH, where R represents an alkyl group. This formula indicates that the alcohol functional group (-OH) is attached to a carbon atom that is also attached to two hydrogen atoms and one R group, making it a primary alcohol. Option C, "CH₂OH," appears to be a typographical error but is intended to represent CH2OH, which aligns with the structure of a primary alcohol.

Question 17

The characteristic grouping of secondary alcohols is…….

Accepted Answer

The characteristic grouping of secondary alcohols is represented by the formula -CHOH, where the carbon atom (C) is bonded to an OH group and two other carbon atoms, indicating its secondary nature.

Question 18

Which of the following are isomers…….

Accepted Answer

Methyl alcohol and dimethyl ether (A) are not isomers as they have different molecular formulas. Ethyl alcohol and dimethyl ether (B) are isomers because they have the same molecular formula (C2H6O) but different structures. Acetone and acetaldehyde (C) are not isomers as they have different molecular formulas. Propionic acid and propanone (D) are not isomers as they have different molecular formulas.

Question 19

The compound HOH₂C - CH₂OH is…….

Accepted Answer

Ethylene glycol is the correct answer because the compound described is HO-CH2-CH2-OH, which matches the structure of ethylene glycol. Ethylene glycol has two hydroxyl groups (-OH) attached to two carbon atoms that are connected by a single bond, fitting the description of the compound given.

Question 20

Methylated spirit is……..

Accepted Answer

Methylated spirit is a mixture of methanol and ethanol, often with other additives, used primarily as a solvent and fuel. Methanol is added to ethanol to make it undrinkable.

Quiz 5: Alkanes and Alcohols