Which of the following is observed in the $C_2H_4$ molecule?

With respect to the compounds $I-V$,choose the correct statement$(s)$.
$(A)$ The acidity of compound $I$ is due to delocalization in the conjugate base.
$(B)$ The conjugate base of compound $IV$ is aromatic.
$(C)$ Compound $II$ becomes more acidic,when it has a $-NO_2$ substituent.
$(D)$ The acidity of compounds follows the order $IV > V > I > II > III$.

The delocalization of $\sigma$ electrons of $C-H$ bond of an alkyl group with the $\pi$ electrons of benzene is observed in

Explain the inductive effect with a suitable example.

The arrangement of $CH_3-CH_2-CH_2-$,$(CH_3)_2CH-$,and $(CH_3)_3C-$ groups in increasing order of their inductive effect ($+I$ effect) is:

The correct stability order of the following species/molecules is: