NET/JRF Important Previous year question and Solution

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Previous paper questions Solution discussion:-

1. Find the correct order of energy for the following molecular orbital is. 

1. 2 Anti molecular orbital,  0 Bonding molecular orbital 

2. 0 Anti molecular orbital, 2 Bonding molecular orbital 

3. 1 Anti molecular orbital,  2 Bonding molecular orbital 

A) 1>2>3

B) 1>3>2

C) 2>3>1

D) 2>1>3

Ans. B

Discussion:-

                    We know that anti molecular orbital energy is greater than Bonding molecular orbital so option B is right answer. 

2. Find the Stereo of given equation in the present of heat . 

  2E, 4Z, 6E Octatriene ------------------>  ?

A) cis

B) Trans

C) Both of above 

D) None of These 

Ans. A

We know that  Octatriene is ( 4n+2 ) system. 

      (4n+2) system show dis rotation in the present of heat. 

Trick:-    O             D                 C

        Opposite     dis               cis

Note :- one key is same or all key is same .

3. Find the Stereo of given equation in the present of heat. 

2E, 4Z, 6Z Octatriene ----------------------->  ?

A) cis

B) Trans 

C) both 

D) None of These 

Ans. B 

We know that Octatriene is (4n+2) system. 

      (4n+2) system show dis rotation in the present of heat. 

Trick:-     O                   D                     C

           Same                dis                 Trans 

Note :- one key is same or all key is same .

   

Some other topics:-

1. Organic reactions|Introduction of Nucleophile and Electrophile