To determine the percentage water content of the fully soaked soil, we need to follow a series of steps to calculate the water content and then express it as a percentage of the dry soil mass. Let's break this down step-by-step.
Step 1: Understand the Problem
We have:
- A bag of dry soil weighing 60 grams.
- An initial volume of water poured into the soil: 50 ml.
- The amount of water that drained through the soil: 35 ml.
Step 2: Calculate the Amount of Water Retained
To find out how much water was retained by the soil, we subtract the amount of water that drained from the initial amount of water added.
[
\text{Water retained} = \text{Initial water} - \text{Water drained}
]
Substituting the values:
[
\text{Water retained} = 50 \, \text{ml} - 35 \, \text{ml} = 15 \, \text{ml}
]
Step 3: Convert Water Volume to Mass
Since the density of water is approximately 1 g/ml, we can convert the volume of water retained into mass. Therefore, 15 ml of water is equivalent to 15 grams.
Step 4: Calculate the Percentage Water Content
The percentage water content of the soil can be calculated using the formula:
[
\text{Percentage water content} = \left( \frac{\text{Mass of water retained}}{\text{Mass of dry soil}} \right) \times 100
]
Substituting the values we have:
[
\text{Percentage water content} = \left( \frac{15 \, \text{g}}{60 \, \text{g}} \right) \times 100
]
Calculating this gives:
[
\text{Percentage water content} = \left( 0.25 \right) \times 100 = 25\%
]
Step 5: Identify the Correct Option
From our calculation, the percentage water content of the fully soaked soil is 25%. Therefore, the correct option is:
B. 25.0
Step 6: Explain Why Other Options Are Incorrect
- A. 46.7: This option is incorrect because it does not reflect the correct calculation of water retained relative to the mass of the dry soil.
- C. 20.0: This option is also incorrect as it underestimates the water content based on the calculations we performed.
- D. 30.0: This option is incorrect as well; it is higher than the calculated percentage and does not align with the data provided.
Summary
- The mass of water retained by the soil is 15 grams.
- The percentage water content is calculated as (mass of water retained / mass of dry soil) × 100.
- The correct answer is 25%, corresponding to option B.
- Always ensure to convert volumes to masses when dealing with water, as the density of water is 1 g/ml.
Revision Summary
- Calculate water retained by subtracting drained water from initial water.
- Convert water volume to mass using the density of water.
- Use the formula for percentage water content: (mass of water retained / mass of dry soil) × 100.
- Verify calculations against provided options to select the correct answer.