In an experiment with Elodea, which change would most likely increase the volume of oxygen gas accumulating at the top of the tube?

Moving the light source closer to the beaker would most likely increase the volume of oxygen gas accumulating at the top of the tube during the experiment with Elodea. This is because Elodea, like other aquatic plants, requires light for photosynthesis, the process by which they convert carbon dioxide and water into glucose and oxygen using light energy.

When the light source is closer, it enhances the light intensity that the Elodea receives. Increased light intensity boosts the rate of photosynthesis, which leads to a greater production of oxygen. Consequently, this increase in oxygen production results in a higher volume of oxygen gas accumulating at the top of the tube.

Other options may have limited effects or could even reduce oxygen production. For example, reducing the size of the beaker does not necessarily enhance the photosynthesis process directly; rather, it could limit the space available for gas exchange. Increasing the water temperature may enhance some aspects of plant metabolism but can also lead to decreased solubility of oxygen. Adding more plants could increase oxygen production to some extent, but without sufficient light, it may not lead to a significant increase in oxygen accumulation compared to simply optimizing the light conditions.