Final answer:
The climax of Chapter IV in 'The Story of My Life' is Helen Keller's revelation as she understands the concept of language when water is spelled into her hand.
Step-by-step explanation:
The climax of Chapter IV in The Story of My Life by Helen Keller is the moment when Helen feels water on her hands and makes the connection between objects and language. This pivotal event signifies her breakthrough in understanding that everything has a name, and these names could be communicated through the finger spelling method.
Prior to this, she had been learning to spell words without comprehending their meaning, exemplified by her interaction with the doll and the spelled word "d-o-l-l," but the episode with the word "water" made her understand that the finger movements represented the concept of water, effectively opening up the world of language to her.