The electron displacement effect observed in the given structures is known as

The higher stabilities of $tert$-butyl cation over isopropyl cation and $trans-2-butene$ over propene,respectively,are due to orbital interactions involving

Which of the following orders of rotation barrier about the $C=C$ bond,as indicated in the structures below,is correct?
$(I)$ $CH_2=CH_2$
$(II)$ $CH_3O-CH=CH_2$
$(III)$ $CH_3O-CH=CH-COOEt$

The interaction between $\pi$ bond and lone pair of electrons present on an adjacent atom is responsible for

Which of the following molecule$(s)$ has/have delocalised lone pair$(s)$ of electrons?

The increasing order of the electron-withdrawing power of the following functional groups is:
a. $-CN$
b. $-COOH$
c. $-NO_2$
d. $-I$