Identify the nature of acetylene

Acetylene is ethyne, with formula: $\mathrm{HC\equiv CH}$

It is a terminal alkyne, so it has an acidic hydrogen atom.

Check reaction with each option

A: $\mathrm{Na}$

Terminal alkynes react with active metals like sodium to form sodium acetylide and hydrogen gas: $2\,\mathrm{HC\equiv CH} + 2\,\mathrm{Na} \rightarrow 2\,\mathrm{HC\equiv CNa} + \mathrm{H_2}$ So, acetylene does react with $\mathrm{Na}$.

B: Ammoniacal $\mathrm{AgNO_3}$

Terminal alkynes react with ammoniacal silver nitrate to form silver acetylide precipitate: $\mathrm{HC\equiv CH} + 2\,[\mathrm{Ag(NH_3)_2}]^+ \rightarrow \mathrm{AgC\equiv CAg} \downarrow + \cdots$ So, acetylene does react with ammoniacal $\mathrm{AgNO_3}$.

C: $\mathrm{HCl}$

Acetylene undergoes addition reaction with hydrogen chloride: $\mathrm{HC\equiv CH} + \mathrm{HCl} \rightarrow \mathrm{CH_2=CHCl}$ (vinyl chloride)

Hence, acetylene does react with $\mathrm{HCl}$.

D: $\mathrm{NaOH}$

Although acetylene is weakly acidic, it is not acidic enough to react with $\mathrm{NaOH}$.

Reason: terminal alkynes are less acidic than substances that can be deprotonated by $\mathrm{OH^-}$. They react with very strong bases like $\mathrm{NaNH_2}$, but not with $\mathrm{NaOH}$.

So, acetylene does not react with $\mathrm{NaOH}$.

Conclusion

The correct option is: $\boxed{\text{D: } \mathrm{NaOH}}$

Comparison with stored correct answer

Stored correct answer: $\mathrm{D}$

Our derived answer is also $\mathrm{D}$, so they agree.