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
