Final Answer:
The correct pH of a 0.450 M HCN solution is approximately 2.35 (Option A).
Step-by-step explanation:
Hydrogen cyanide (HCN) is a weak acid that partially ionizes in water, forming cyanide ions (CN-) and hydronium ions (H3O+). The pH of a solution can be calculated using the formula:
pH = -log10[H3O+]
For a weak acid like HCN, the concentration of H3O+ is determined by the extent of ionization. Given a 0.450 M HCN solution, you can set up an equilibrium expression and use the dissociation constant (Ka) for HCN to find the concentration of H3O+. Substituting this value into the pH formula gives the correct pH of approximately 2.35.
Option A is the answer.