Metallic sodium does not react normally with:

Step 1: Na reacts with acidic H compounds

• $\ce{2Na + 2H2O -> 2NaOH + H2}$ (water)
• $\ce{2Na + 2ROH -> 2RONa + H2}$ (alcohols)
• $\ce{2Na + 2NH3 -> 2NaNH2 + H2}$ (ammonia)
• $\ce{Na + HC≡CH -> NaC≡CH + \frac{1}{2}H_2}$ (terminal alkynes, pKa ~25)

Step 2: Classify Each Option

• (a) Gaseous $\ce{NH3}$: has acidic N-H, reacts with Na. Reacts.
• (b) Tert-butyl alcohol: has -OH (acidic), reacts with Na (slowly).
• (c) But-2-yne ($\ce{CH3-C≡C-CH3}$): internal alkyne, NO terminal C-H on triple bond. No acidic H accessible. Does NOT react.
• (d) Ethyne ($\ce{HC≡CH}$): terminal alkyne, sp C-H is acidic (pKa 25). Reacts with Na.

But-2-yne = internal alkyne = no reaction with Na.

Key Points:

• Na reacts with O-H, N-H, and terminal alkyne C-H (sp, pKa ~25)
• Internal alkynes have no terminal sp C-H; no reaction under normal conditions