When you answer a question using one word should put period after it?

No, it is not correct to put a period after a one-word answer to a question. A period is used to indicate the end of a complete sentence, and a one-word answer does not constitute a complete sentence. For example, if someone asks you, "How are you?" and you respond with "Fine," there is no need to put a period after the word "Fine" because it is not a complete sentence.