Test: Physical and Chemical properties (January 26) - NEET MCQ

The correct answer is Option A.

The compounds CCl₄ have zero dipole moment as the individual bond dipoles cancel each other.

The correct answer is Option B.

The chiral carbon atom is one in which there are an unequal number of carbon atoms, this happens only in option (B) as it forms a non superimposable mirror image.

The correct answer is option C
The reaction of phenol with NaOH and CO₂ is known as Kolbe-Schmidt or Kolbe’s reaction. The product formed is salicylic acid.

The correct answer is Option A.
Ethyl magnesium bromide: CH3CH2−Mg−Br
Organometallic compounds are those compounds in which carbon atoms are directly linked to metal. 
It contains at least one bond between a carbon atom and a metal.

The correct answer is Option B.
Both give the same product (alkene) on reaction with alc. KOH.
 

The correct answer is option A
Reactivity of alkyl halides towards SN1 nucleophilic substitution reaction is 3^o > 2^o > 1^o because in SN₁ nucleophilic reaction, the first and the slow step is the formation of a carbocation. Tertiary carbocation is more stable than a secondary carbocation which is more stable than a primary carbocation. Greater the stability of the carbocation, greater will be the ease of formation of carbocation, and hence faster will be the rate of the reaction.

On going down the group size of the halides increases and hence stability of the compound decreases as bond length is going to increase resulting in easy break down of the bond and hence reactivity increases. 

Thus the correct order of the reactivity is:

R-I >R-Br> R-Cl

The correct answer is option C
Nucleophilic substitution reaction on an optically active alkyl halide gives a mixture of enantiomers.
Because the reaction occurs by SN​1 mechanism.
SN​1 mechanism involves racemisation as the nucleophile can attack from either side. In SN​2 reaction, inversion of configuration is involved as the nucleophile can attack from the opposite side.

In dehydrohalogenation reactions the preferred product is that alkene which has the greatest number of alkyl groups attached to the doubly bonded carbon atoms. This rule is also known as Saytzeff’s rule.