To determine which list shows the acids in order from the strongest conjugate base to the weakest conjugate base, we first need to understand the relationship between acids and their conjugate bases. The stronger the acid, the weaker its conjugate base will be.
The acids in question are:
- H₂Se (hydroselenic acid)
- BrH (hydrobromic acid)
- AsH₃ (arsine)
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BrH (hydrobromic acid) is a strong acid because bromine is a halogen and hydrobromic acid readily dissociates in solution. Its conjugate base, Br⁻ (bromide ion), is thus quite weak.
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H₂Se (hydroselenic acid) is a weaker acid than BrH, thus its conjugate base, Se²⁻ (selenide ion), is stronger than Br⁻.
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AsH₃ (arsine) is a very weak acid compared to both H₂Se and BrH, making its conjugate base, As³⁻ (arsenide ion), the strongest of the three.
Therefore, we can order the conjugate bases from strongest to weakest as follows:
- As³⁻ (from AsH₃) > Se²⁻ (from H₂Se) > Br⁻ (from BrH).
This leads us to the order of the acids from the strongest conjugate base to the weakest conjugate base:
AsH₃ > H₂Se > BrH.
Thus, from your options, the correct answer is:
AsH3, H2Se, BrH.