The steps in a reaction mechanism are as follows. Which species is acting as a catalyst? Step 1: Ag+(aq) + Ce4+(aq) <> Ag2+(aq) + Ce3+(aq) Step 2: Tl+(aq) + Ag2+(aq) > Tl2+(aq) + Ag+(aq) Step 3: Tl2+(aq) + Ce4+(aq) > Tl3+(aq) + Ce3+(aq)

Ag⁺ acts as the catalyst.

Explanation:

Hello,

In this case, each step is reorganized:

- Step 1:

- Step 2:

- Step 3:

In such a way, Ag⁺ is converted to Ag²⁺ in the first step, but then it is regenerated to simple Ag⁺, therefore, Ag⁺ acts as the catalyst.

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it's c. elements are placed in rows based on how may valencies electrons have.