It is saying due to sir there will be no reso on a.. but there is reso in ring?

it is saying no reso on A.. how can it be possible

Steric inhibiting resonance is abbreviated as SIR in organic chemistry .It inhibits resonance in any molecule by distorting the planar structure of the molecule which is essential requirement of a molecule to exhibit resonance

If there is two bulky group in ortho substituted compound the repulsion between them lead to send the gropu out of the benzene plain. Hence Resonance get stopped

sir. here isopropyl grp will be out of plane na.. but benzene ring will remain on plane. Here only reso is occurring on benzene ring.. how it will change resonin benzene ring then?

due to bulky groups repulsion in 1st compound loss its planarity results no resonance..

benzene ring will lose planarity?

only ortho is bulky...attached in benzene sourav..

but it is saying reso will not occur on A and occur on B?

when planarity lose stop the resonance

sir but isopropyl grp is not involved in reso with benzene ring na? so how any effect on isopropyl grp will affect reso?

https://youtu.be/iHX3npAkbOk

but sir there is no effect on ring na.. no reso happening is on ring.. so why there will be no reso

SIR makes the group attached out of plane and not the ring na?

sourav resonance nhi hoga....bs steric repulsion ortho grp ke wajah se unstable hoga

sir.. Resonance to ring mai ho rha hai na? SIR will make isopropyl grp go out of plane and not the benzene ring.. so how reso will be affected

Resonance effect nhi ho rha hai bs SIR se isopropyl grp out of plane chala jayega

sir dono mai reso same hai na? due to benzene ring?

sourav yha repulsion se stability compare kr diya hai...but agar acidity or basicity me aisa case aaye then you can compre this effectively