Which among the following functional groups exhibits $-R$ effect?

Which among the given acids has the lowest $pKa$ value?

Which among the following pairs of electronic effect and its example is $NOT$ correct?

Which of the following statements are $TRUE$?
$(I)$ Inductive effect operates through the $\sigma$ bond
$(II)$ Resonance effect operates through the $\pi$ bond
$(III)$ Inductive effects operate through the $\pi$ bond
$(IV)$ Resonance effect operates through the $\sigma$ bond

Which one of the following orders is correct regarding the inductive effect of the substituents?

In compound $(X)$,hyperconjugation is present and in $(Y)$,resonance effect is present. What are $X$ and $Y$,respectively?