The following sentence has been divided into four segments. Identify the segment that contains an adverbial usage error.
Mrs. Gomathi was / that tired and weak / that she could / scarcely walk.

The error lies in the segment "that tired and weak". In English grammar, the correlative conjunction structure "so... that" is used to express cause and effect. "That" should be replaced with "so" to make the sentence grammatically correct: "Mrs. Gomathi was so tired and weak that she could scarcely walk."