Q56 of 66 Page 154

In the following questions a statement of Assertion (A) followed by a statement of

Reason (R) is given. Choose the correct option out of the choices given below each question.


Assertion (A): Energy of resonance hybrid is equal to the average of energies of all canonical forms.


Reason (R): Resonance hybrid cannot be presented by a single structure.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct.


A is not correct but R is correct.

We know that the resonance hybrids are always more stable than any of the canonical structures because of the resonance energy.


The energy of orbitals is lowered by the delocalisation of the electrons in resonance, and as the energy is decreased the stability increased, and the amount of energy which is reduced, due to resonance, this energy is called resonance energy.


A canonical structure which is having lower energy,have a greater contribution to resonance hybrid.


Hence, Assertion is not correct but reason is correct.


Option (iv) is correct.


More from this chapter

All 66 →
54

Match the ions given in Column I with their nature given in Column II.


 55

In the following questions a statement of Assertion (A) followed by a statement of

Reason (R) is given. Choose the correct option out of the choices given below each question.


Assertion (A): Simple distillation can help in separating a mixture of propan-1-ol (boiling point 97°C) and propanone (boiling point 56°C).


Reason (R): Liquids with a difference of more than 20°C in their boiling points can be separated by simple distillation.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct.


 57

In the following questions a statement of Assertion (A) followed by a statement of

Reason (R) is given. Choose the correct option out of the choices given below each question.


Assertion (A): Pent- 1- ene and pent- 2- ene are position isomers.


Reason (R): Position isomers differ in the position of functional group or a substituent.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv)A is not correct but R is correct.


 58

In the following questions a statement of Assertion (A) followed by a statement of

Reason (R) is given. Choose the correct option out of the choices given below each question.


Assertion (A): All the carbon atoms in H2C = C = CH2 are sp2 hybridised


Reason (R): In this molecule all the carbon atoms are attached to each other by double bonds.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct.