Jose’s lab instructor gives him a solution of sodium phosphate that is buffered to a pH of 4. Because of an error that he made while calibrating the pH meter, Jose’s measurements of the pH of the sodium phosphate solution are 5.4, 5.4, and 5.4. Which statement best describes his results?
Answer
A
They are precise but not accurate.
B
They are both precise and accurate.
C
They are neither accurate nor precise.
D
They are accurate but not precise.
Explanation
The correct pH is 4, but Jose’s measurements are all 5.4, so they are not close to the true value and are not accurate. Since the three measurements are identical to one another, they are consistent and therefore precise. The best description is “precise but not accurate.”
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