To determine which solution was at the optimal temperature to allow for the greatest solubility, we need to compare the solubility values given in the chart.
The chart provides the solubility (in grams per 100 grams of water) for each solution at a specific temperature:
1. For solution W at 40°C, the solubility is 50 g/100 g water.
2. For solution X at 59°C, the solubility is 200 g/100 g water.
3. For solution Y at 55°C, the solubility is 150 g/100 g water.
4. For solution Z at 48°C, the solubility is 80 g/100 g water.
By comparing these solubility values, we observe the following:
- Solution W: 50 g/100 g water
- Solution X: 200 g/100 g water
- Solution Y: 150 g/100 g water
- Solution Z: 80 g/100 g water
Clearly, Solution X has the highest solubility with 200 g of solute per 100 g of water.
Therefore, the solution that was at the optimal temperature to allow for the greatest solubility is:
[tex]\[
\boxed{X}
\][/tex]
