To determine the order of acids from strongest to weakest, we can look at the electronegativity of the elements involved and how that affects the strength of the acids.
1. **HCl (hydrochloric acid)**: HCl is a strong acid because chlorine (Cl) is highly electronegative. It stabilizes the negative charge on the chloride ion (Cl⁻), making it more willing to donate a proton (H⁺).
2. **H₂S (hydrosulfuric acid)**: H₂S is a weak acid compared to hydrochloric acid. Sulfur (S) is less electronegative than chlorine, which means it doesn't stabilize the negative charge as effectively as Cl does when H⁺ is lost, making H₂S a weaker acid than HCl.
3. **PH₃ (phosphine)**: PH₃ is not typically considered an acid in aqueous solution and does not donate protons readily. Therefore, it is weaker than both HCl and H₂S.
Based on this analysis, the strongest to weakest order of acids is:
**HCl > H₂S > PH₃**
Thus, the correct response is:
**HCl, H2S, PH3**