Test: JEE Previous Year Questions- Alcohols - JEE MCQ

Dehydrated product will be conjugated with −C=O that's why more tendency and as carbocation is more stable further to C=O that's why (b)   

The correct answer is option D
LiAlH4​ can reduce the carboxylic acid group without affecting the double bond because alkene is electron-rich species.

The ease of dehydration of alcohols is tertiary > secondary > primary according to the order of stability of the carbocations.

The more stable carbocation is generated, thus more easily it will be dehydrated.

Vapor density = Molecular weight/2

As both the compounds have same molecular weights, both will have the same vapour density. Hence, gaseous density of both ethanol and dimethyl ether would be same under identical conditions of temperature and pressure. The rest of these three properties; Vapour pressure, boiling point and heat of vaporization will differ as ethanol has hydrogen bonding whereas ether does not.

Methyl vinyl ether is a very reactive gas. It is hydrolysed rapidly by dilute acids at room temperature to give methanol and aldehyde. However, under anhydrous conditions at room temperature, it undergoes many addition reactions at the double bond.

Electrophilic addition reaction more favourable.

Correct Answer is option C
When ethanol is treated with a mixture of phosphorus and iodine, ethyl iodide CH₃​CH₂​I is obtained. 
 
Compound A on reaction with Mg metal in ether forms ethyl magnesium iodide CH₃​CH₂​ MgI. 
 
The compound B reacts with formaldehyde to form compound C; CH_3​CH₂​−CH₂​−OMgX which on hydrolysis gives n propyl alcohol CH₃​CH₂​CH₂​−OH.
 
The compound D is n-propyl alcohol. 
 
Hence, option C is correct.
 

The fruity smell is evolved due to the formation of ester when ethanol and acid are treated in the presence of concentrated H2​SO4​.
The reaction is
CH₃​COOH + CH_3​CH₂​OH → CH₃​COOC₂​H_5​

A mixture of conc.HCl and anhydrous ZnCl₂
​
 is called Lucas reagent.
 
Primary alcohols react with Lucas reagent very slowly on heating to give alkyl chlorides.
Secondary alcohols react with Lucas reagent much faster.
Tertiary alcohols instantaneously react with HCl at room temperature.
 
Note: Lucas reagent is required for primary and secondary alcohol only.

Whenever dehydration can form two different alkenes major product is formed according to sides of rule that is more substituted alkene or alkene having lesson number of hydrogen atoms on the to double bonded carbon atoms is the major product. 

Such reactions which can produce two or more structural isomers but one of them in Greater amount than the others are called ratio selective encasa reaction is hundred percent regioselective it is termed as reduce specific

In addition to being reduced selective alcohol dehydration are stereoselective reaction in which a single starting material can yield two or more stereoisomeric products but give one of them in Greater amount than any other