The sentence यत् पच्यते सः पाकः contains यत्-तत् pair. Usually, both of these words are found to have the same properties of gender and number.

In the above sentence, यत् is paired with सः to indicate the intention of the speaker that he refers to some non-specific item using यत् and a specific word पाकः using सः (as a विशेषणम्).

Can the formation of this sentence be considered grammatically valid?