Question

laboratory simulation
question
why is a 3% sodium bicarbonate (nahco₃) solution added to each test tube?
select all that apply.
a. its volume changes due to photosynthesis.
b. it is a source of carbon dioxide.
c. it is a ph indicator.
d. it is a source of water.
e. it is a source of oxygen.
submit

Explanation:

• Option A: In photosynthesis - related experiments, the volume change (e.g., gas production/consumption) can be observed, and the $NaHCO_3$ solution's role is to provide $CO_2$, and the volume may change due to photosynthesis (e.g., oxygen production increasing volume).
• Option B: Sodium bicarbonate ($NaHCO_3$) decomposes or reacts to release $CO_2$, which is a reactant for photosynthesis, so it is a source of $CO_2$.
• Option C: $NaHCO_3$ is not a pH indicator (pH indicators are substances like litmus, phenolphthalein), so C is wrong.
• Option D: The solution contains water, so it can be a source of water for the experiment (e.g., for aquatic plants in the test tube).
• Option E: $NaHCO_3$ does not provide oxygen directly (oxygen in photosynthesis comes from water splitting), so E is wrong.

Answer:

A. Its volume changes due to photosynthesis, B. It is a source of carbon dioxide, D. It is a source of water