The best graph to show which dissolves better in water, salt or baking soda, would be a bar graph. Here's why:

* Easy to compare: Bar graphs make it very easy to visually compare the heights of the bars representing the solubility of salt and baking soda.

* Direct comparison: You can easily see which bar is taller, indicating the substance that dissolves more.

* Clear labeling: You can label the x-axis with the substances (salt and baking soda) and the y-axis with the amount dissolved (e.g., grams per 100 mL of water).

Here's how you would set up the graph:

1. X-axis: "Substance" (salt and baking soda)

2. Y-axis: "Solubility" (grams dissolved per 100 mL of water)

3. Bars: Two bars, one for salt and one for baking soda. The height of each bar represents the amount of that substance that dissolved in a set volume of water.

Important Note: To make a fair comparison, you would need to dissolve both salt and baking soda in the same volume of water at the same temperature.