Answer:
Option-D " H-C≡N: " is the correct answer.
Step-by-step explanation:
The valency of Hydrogen is one because it has only one electron in its valence shell. i.e.
H = 1 = 1s¹
The valency of Carbon is four because it has four unpaired electrons in its valence shell. i.e.
C = 6 = 1s², 2s¹, 2px¹, 2px¹, 2pz¹
The valency of Nitrogen is four because it has three unpaired electrons and in its valence shell. i.e.
N = 7 = 1s², 2s², 2p¹, 2py¹, 2pz¹
Hence, Hydrogen will share one electron with carbon making one single bond, Carbon will share one electron with hydrogen making a single bond and three electrons with Nitrogen making a triple bond, while, nitrogen will share three electrons with Carbon making a triple bond, also the lone pair of electrons on Nitrogen are specified as double dots on a lewis structure.