Answer: The noun clause in the first sentence is "Whatever you do", while the noun clause in the second sentence is "what she should major in at college".
Step-by-step explanation: A noun clause is a dependent clause, that is to say a clause that does not express a full thought, which functions as a noun. Moreover, a noun clause is generally introduced by a relative pronoun. In the first sentence, the noun clause is "Whatever you do" and it is functioning as the subject of the sentence, while in the second sentence, the noun clause is "what she should major in at college" and it is performing the function of direct object. Therefore, both of them are acting as nouns.