Classify the following groups as electron-withdrawing ($-I$ effect) or electron-donating ($+I$ effect) inductive effect groups: $-CH_3, -Cl, -NO_2, -(CH_3)_3C, -OC_6H_5, -C_6H_5, -OH, -NH_2, -CH_2CH_3$.

Which of the indicated $H$ in the following is most acidic?

$x =$ number of compounds that are better hydride donors than $Ph-CH(O^{\Theta})_2$.

The decreasing order of reactivity towards electrophilic substitution for the following compounds is:

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

State True or False for the following statements regarding the $-NO_2$ group in nitrobenzene:
$(i)$ In resonance,it acts as an electron-donating group,and in the inductive effect,it acts as an electron-attracting group.
$(ii)$ It acts as an electron-donating group in both resonance and the inductive effect.
$(iii)$ It acts as an electron-attracting group in both resonance and the inductive effect.
$(iv)$ It acts as an electron-attracting group in resonance and an electron-donating group in the inductive effect.