Here's why:

* Central atom: Carbon (C) is the central atom.

* Valence electrons: Carbon has 4 valence electrons, Hydrogen has 1, and Nitrogen has 5.

* Bonding: Carbon forms a single bond with Hydrogen and a triple bond with Nitrogen.

* Hybridization: Carbon undergoes sp hybridization, resulting in two linear hybrid orbitals.

* Geometry: Due to the linear sp hybrid orbitals, the HCN molecule assumes a linear shape with a bond angle of 180 degrees.

Essentially, all three atoms are arranged in a straight line.