Answer :

To determine how many grams of solute are in 125 mL of a 5% solution, we will follow a step-by-step process:

1. Understanding the Percentage Concentration: A 5% solution means that there are 5 grams of solute in every 100 mL of the solution.

2. Determine the Equivalent for 125 mL:
- We need to find out how many grams of solute would be present in 125 mL of solution.

3. Set Up a Proportion:
- Since 5 grams of solute are present in 100 mL of solution, we can set up a proportion to find out the amount of solute in 125 mL.
- The proportion is [tex]\((5 \text{ grams of solute} / 100 \text{ mL of solution}) = (x \text{ grams of solute} / 125 \text{ mL of solution})\)[/tex].

4. Solve the Proportion:
- Cross-multiplying to solve for [tex]\(x\)[/tex], we get:
[tex]\[ 5 \text{ grams} \times 125 \text{ mL} = 100 \text{ mL} \times x \text{ grams} \][/tex]
- Simplifying this equation, we have:
[tex]\[ 625 = 100x \][/tex]
- Dividing both sides by 100 gives us:
[tex]\[ x = \frac{625}{100} = 6.25 \text{ grams} \][/tex]

Therefore, there are 6.25 grams of solute in 125 mL of a 5% solution.

Considering the given options:
- a. 5.25 g
- b. 6.25 g
- c. 69 g
- d. 5 g

The correct answer is:
O b. 6.25 g