Question

unit review - matter and change
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a 250 g sample is composed of 131 g of potassium (k) and 119 g of chloride (cl). what is the percent by mass of k in the sample?
47.6%
20.2%
81.3%
52.4%

Explanation:

Step1: Define mass percent formula

Percent by mass of K = $\frac{\text{Mass of K}}{\text{Total mass of sample}} \times 100\%$

Step2: Substitute given values

Mass of K = 131 g, Total mass = 250 g
Expression: $\frac{131}{250} \times 100\%$

Step3: Calculate the result

First compute $\frac{131}{250}=0.524$, then multiply by 100%: $0.524 \times 100\% = 52.4\%$

Answer:

52.4% (corresponding to the option: 52.4%)