Which of the following can be mixed in solution with H2CO3 to make a buffer? O A. NH3 O B. HF O C. NaHCO3 O D. Na2CO3​

When can a hypothesis be elevated to the status of a theory? a) when it is validated by an experiment b) when data gathered from an experiment precisely fits predictions c) when it can be proved to be true d) when it meets the test of repeated experimentation