What are the characteristics of the inductive effect?

The decreasing order of acidity of the following terminal acetylenes is:

In the compound given below,the correct order of the acidity of the positions $(X)$,$(Y)$ and $(Z)$ is:

Which of the following does not show hyperconjugation?

Given below are two statements:
Statement $I$: In $O_2N-C_6H_4-CH^+-C_6H_4-OCH_3$, the carbocation is stabilised by $+R$ effect of $-OCH_3$ group.
Statement $II$: In $O_2N-C_6H_4-CH^--C_6H_4-OCH_3$, the carbanion is stabilised by $-R$ effect of $-NO_2$ group.
In the light of the above statements, choose the correct answer from the options given below:

Among the following,the most acidic compound is