John is testing the effect of temperature on the solubility of sugar in water. He plans to determine the mass of sugar dissolved in a saturated solution. He will begin with a known mass of sugar and add sugar to water until the solution is saturated. He will then calculate how much sugar dissolved by subtracting the remaining mass from the initial mass.

He organized data about his experiment in the following table:

| | Group A | Group B | Group C |
|------------------|----------|---------|---------|
| Volume of water | 100 mL | | |
| Temperature | 25°C | | |
| Initial mass of sugar | 1000 g | | |
| Final mass of sugar | 800 g | | |

Which factor should be the same in all three groups?

A. Final mass of sugar
B. Temperature
C. Initial mass of sugar
D. Volume of water



Answer :

To determine the factor that should be the same across all groups in John's experiment, we need to ensure that the solubility of sugar solely depends on the temperature variation while keeping other variables constant.

Here’s a detailed, step-by-step explanation:

1. Volume of Water:
- Different volumes of water could affect the amount of sugar that can dissolve, as solubility is often related to the volume of the solvent.
- Therefore, the volume of water across different groups must be consistent to maintain fairness.

2. Temperature:
- John is testing the effect of temperature on the solubility of sugar.
- To see the impact of temperature changes, it is essential to vary temperatures across different groups.
- Therefore, the temperature should not be the same in all groups as it is the variable being tested.

3. Initial Mass of Sugar:
- The initial amount of sugar added to the solution must be the same for all groups, to ensure that any observed differences in dissolved sugar are due to the temperature change alone, not the amount of starting sugar.
- Inconsistent initial masses would lead to variability that could obscure the effect of the temperature.

4. Final Mass of Sugar:
- This is the variable that is being measured after establishing a saturated solution.
- Different groups will have different final masses as a result of varying temperatures, so this should not be the same across all groups.

Given this reasoning, the factor that should be the same in all groups is:
C. Initial mass of sugar