The current scientific verdict on the phlogiston theory demonstrates which two of the following principles?

Scientific theories can be replaced by better theories.

An experiment can disprove a theory that scientists have accepted.

Scientific knowledge is absolute and can never change.

Current scientific theories must be entirely correct.

A single experiment can prove that a scientific theory is correct.

The two valid principles are:

Scientific theories can be replaced by better theories. An experiment can disprove a theory that scientists have accepted.

Explanation:

The scientific knwoledge is not inmutable; it may (and does) change with new discoveries.

In fact, scientific theories cannot be proved right, instead they are constantly tested to try to disprove them. This is what the principle that theories are falsiable means.

As long as a scientific theory is not disproved it remains valid, but new discoveries may lead, eventually, to its disprovement.

Scientific knowledge evolves because new procedures, new technologies, and new evidence leads to a better understanding and better explanations.