The alkyne that will give a white precipitate with silver trioxonitrate(V) is

Correct answer: CH₃CH₂CH₂CH₂C≡CH (Option C)

Explanation: Terminal alkynes (with a ≡C–H group) have an acidic hydrogen that reacts with ammoniacal silver trioxonitrate(V) (AgNO₃) to form a white precipitate of silver acetylide (AgC≡CR). Internal alkynes lack this terminal hydrogen and do not give the precipitate.

• CH₃CH₂C≡CCH₂CH_3} — internal alkyne → no precipitate.
• CH₃C≡CCH₂CH₂CH_3} — internal alkyne → no precipitate.
• CH₃CH₂CH₂CH₂C≡CH — terminal alkyne → gives white Ag acetylide.
• CH₃CH₂CH₂C≡CCH₂CH_3} — internal alkyne → no precipitate.

Note: The classic test is done with ammoniacal AgNO₃; terminal alkynes form explosive metal acetylides, so this test is handled with care.