A solution of butanoic acid is prepared from 0.067 mol of butanoic acid in sufficient water to give 1.0 L of solution and has a pH of 2.72. Determine the Ka for the butanoic acid solution. Show all calculations and report your answer to the correct number of sig figs.

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Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?

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