Answer:
a. Here, the yellow precipitate is lead (II) iodide:

b. Here the white precipitate is barium sulfate:

c. Here the brown precipitate is iron (III) hydroxide:

d. Here, the precipitate is copper (II) hydroxide:

Explanation:
Hello.
In this case, since the precipitation reactions are characterized by the formation of a product which is highly insoluble in water, specially very heavy products having heavy metals at the cations, for each case we proceed as follows:
a. Here, the yellow precipitate is lead (II) iodide:

b. Here the white precipitate is barium sulfate:

c. Here the brown precipitate is iron (III) hydroxide:

d. Here, the precipitate is copper (II) hydroxide:

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