Question

A 400 g sample is composed of 100 g of cesium (Cs) and 300 g of iodine (1).

What is the percent by mass of Cs in the sample?

A. 50.0%
B. 70.0%
C. 25.0%
D. 75.0%​​​​

Answer 1

Answer: C. 25%

Step-by-step explanation: This is a basic probability problem. First, you must find the total which is in question. 400 grams is the total in this case. The Cs make up 100 grams of this. Next, you put the part over the whole, and divide. 100/400= 0.25. When you want to find the probability with the probability sign, you move the decimal place two points to the right and then add the sign. Hence, 25%.