Final answer:
The conjugate base of HF (F-) is weaker than the conjugate base of HCN (CN-), making HF a stronger acid than HCN.
Step-by-step explanation:
The statement about the conjugate bases of hydrofluoric acid (HF) and hydrocyanic acid (HCN) that is correct is that the conjugate base of HF (F-) is weaker than the conjugate base of HCN (CN-).
The strength of a conjugate base is determined by the stability of the negative charge it carries. In HF, fluorine (F) is more electronegative and can better stabilize the negative charge on F-. In HCN, carbon (C) is less electronegative and cannot stabilize the negative charge on CN- as effectively.
Therefore, because F- is a weaker base than CN-, HF is a stronger acid than HCN.