- A. H\(_2\)O: Water has a bent shape due to the lone pairs on oxygen, making the geometry bent.
- B. Acetylene: Acetylene is a linear molecule with a triple bond between the carbons.
- C. NH\(_3\): Ammonia has a trigonal pyramidal shape due to the lone pair on nitrogen.
- D. ClO\(_2\): Chlorine dioxide is a bent molecule due to the lone pairs on chlorine.
Thus, the correct matching is A-I, B-II, C-III, D-IV.