ECAT Pre Engineering Chemistry Chapter 21 MCQ Test With Answer

When metallic sodium in ether is heated with ethyl chloride, which alkane is formed

• Propane A
• Ethane B
• Iso-butane C
• N-butane D

Grignard reagent is not prepared in aqueous medium but prepared in ether medium because

• The reagent is highly reactive in ether A
• The reagent does not react with water B
• The reagent becomes inactive in water C
• The reagent reacts with water D

The alkyl halide molecule on which a nucleophile attacks is called

• Substrate A
• Subsituent B
• Substituted C
• All of these D

When alkyl halides are heated with aqueous solution of ammonia at about 100°C, amines are formed. This reaction is known as

• Williamsons synthesis A
• GHoffmans reaction B
• Wurtz reaction C
• Clemensen reaction D

SN₂ reaction has order of reaction :

• First A
• Second B
• Third C
• Zero D

Grignard reagent is reactive due to :

• The presence of halogen atom A
• The presence of Mg atom B
• The polarity of C - Mg bond C
• None of them D

The compounds or species in search of electrons are called

• Elctrophiles A
• Nucleophile B
• Nitrities C
• Bases D

If Grignard reagent is allowed to react with another alkyl halide the main product is

• An alkane A
• Cyclo alkane B
• Alkyne C
• An alkene D

The rate of E₁reaction depends upon:

• The concentration of substrate A
• The concentration of nucleophile B
• The concentration of substrate as well as nucleophile C
• None of these D

The reaction between primary amine-chloroform and alcoholic caustic potash is called

• Wurtz reaction A
• Frankland reaction B
• Cannizzaro's reaction C
• Carbylamine reaction D

Alcohol can be prepared from Grignard's reagent with an aldehyde: If we start with formaldehyde the product alcohol with be

• Primary A
• Secondary B
• Territory C
• Aromatic D

Reduction of alkyl halides give

• Alkanes A
• Alkenes B
• Ketones C
• Ether D

Alkyl halides react with Mg in dry ether to form

• Magnesium halide A
• Grignard's reagent B
• Alkene C
• Alkyne D

Which is a weak nucleophile

• OH^- A
• Br^- B
• NH₃ C
• CI^- D

Ethyl bromide on treatment with alcoholic KOH gives

• Ethylene A
• Ethanol B
• Acetic Acid C
• Ethane D

E₂has molecularity :

• One A
• Two B
• Three C
• Half D

By simply reacting Grignand's reagent with water we get

• An alkane A
• Higher alkane B
• An alkene C
• An alkyne D

Elimination bimolecular reactions involve:

• First order Kinetics A
• Third order kinetics B
• Zero order kinetics C

Alkanes may be prepared by the reaction of alkyl halides with

• Alcohol A
• Carboxylic acid B
• Grignard reagents C
• None of these D

• Electronphilic substitution A
• Electrophilic addition B
• Free radical substitution C
• Nuclephilic substitution D

The elimination of hydrogen halide from adjacent carbon atoms is called

• Dehydrogenation A
• Hydrogenation B
• Dehydrohalogenation C
• Hydrohalogenation D

Alkyle halides can be prepared by treating halogen acids with

• Ethane A
• Ethanol B
• Ethene and ethanol C
• Aldehyde D

A carbon atom carrying a postitive charge and attached to three other atoms of groups is called

• Caronium ion A
• Carbanion B
• Oconium ion C
• Carba ion D

SN2 reaction can be best carried out with

• Primary alkyl halides A
• Secondary alkyl halides B
• Tertiary alkyl halides C
• All the three D

Which one of the following will have the maximum dipole moment

• CH₃F A
• CH₃Cl B
• CH₃Br C
• CH₃l D

Which of the following chlorocompounds is heat easily hydrolysed by hydorxide ion to give the product indicated

• 
  A
• 
  B
• 
  C
• 
  D

Grignad reagent is reactive due to

• The presence of halogen atom A
• The presence of Mg atom B
• The polarity of C - Mg bond C
• None of above D

Replacement of Cl of Chlorobenzene to give phenol requires drastic conditions but chlorine of 2, 4-Dinitrochlorobenzene is readily replaced because

• NO₂makes the electron rich ring at ortho and para positions A
• NO₂withdraws electrons at metaposition B
• NO₂donate electrons at m-position C
• NO₂withdraws electrons at ortho and para position D

1, 3-Dibromopropane reacts with metallic zinc to form

• Propene A
• Propane B
• Cyclopropane C
• Hexane D

Ethyl bromide is formed by the reaction of HBr with

• Ethane A
• Ethene B
• Ethyne C
• Propane D