1. An experiment measured 45 mL , but the actual value is 50 mL . What is the percent error? \( \begin{array}{llll}\text { a) } 10 \% & \text { b) } 9 \% & \text { c) } 12.5 \% & \text { d) } 5 \%\end{array} \)

To find the percent error, use the formula: \[ \text{Percent Error} = \left( \frac{\text{Actual Value} - \text{Measured Value}}{\text{Actual Value}} \right) \times 100 \] Substituting in the values: \[ \text{Percent Error} = \left( \frac{50 \, \text{mL} - 45 \, \text{mL}}{50 \, \text{mL}} \right) \times 100 = \left( \frac{5 \, \text{mL}}{50 \, \text{mL}} \right) \times 100 = 10\% \] So the answer is **a) 10%**! It's always good practice to double-check calculations when it comes to percent errors. A common mistake is misreading the values or applying the formula incorrectly. Remember to focus on the actual value as the denominator to get accurate results!