Question

a teacher picks a leaf from a tree outside her classroom that has been exposed to sunlight for several hours. she submerges it in water and bubbles form on the leaf.
what is the best possible explanation for this?
a. bubbles form because of the change in the temperature of the water.
b. carbon dioxide from the water is forming bubbles around the leaf.
c. the density of the water changes, causing bubbles to form.
d. the leaf is producing oxygen gas.
e. the sunlight is causing the water to boil.

Explanation:

Plants perform photosynthesis in the presence of sunlight. The chemical equation for photosynthesis is \(6CO_2 + 6H_2O
ightarrow C_6H_{12}O_6+6O_2\). Oxygen (\(O_2\)) is a by - product of photosynthesis. When the leaf (which was exposed to sunlight and thus was photosynthesizing) is submerged in water, the oxygen gas produced during photosynthesis forms bubbles.

• Option A: There is no indication that the temperature of the water is changing in a way that would cause bubbles (like boiling).
• Option B: Carbon dioxide (\(CO_2\)) is taken in during photosynthesis, not released as a gas in this context to form bubbles.
• Option C: There is no information suggesting a density change in water that would cause such bubbles.
• Option E: Sunlight does not cause water to boil in this scenario (boiling point of water is \(100^{\circ}C\) at standard pressure, and sunlight on a leaf - water system won't reach that temperature).

Answer:

D. The leaf is producing oxygen gas.