Science / Chemistry / Trueness: Trueness is the closeness of an average measurement to a 'true' value, while accuracy is the the closeness of a single measurement to the true value.
Science / Chemistry / Indicator: A substance that undergoes an sharp, easily observable change when conditions in its solutions change. See, for example, acid-base indicator and redox indicator. MORE
Science / Chemistry / Accuracy: Compare with precision and trueness. Accuracy is the correctness of a single measurement. The accuracy of a measurement is assessed by comparing the measurement with the true or accepted value, based MORE