Write the balanced chemical symbol equation for photosynthesis.

Students carry out an experiment to test a leaf for the presence of starch to verify that photosynthesis has taken place. The method they follow is outlined below:

1. Place the leaf in a beaker of boiling water for $30seconds$.
2. Turn off the Bunsen burner flame.
3. Using forceps, transfer the leaf into a boiling tube half-filled with ethanol. Place this tube into the hot water in the beaker.
4. Once the leaf has lost its green colour, remove it and dip it into warm water for a few seconds.
5. Spread the leaf flat on a white tile and add a few drops of iodine solution.

(i) Explain the safety hazard associated with step 3 and why step 2 is necessary to minimize this risk. (ii) State the biological purpose of placing the leaf in boiling water in step 1. (iii) State the purpose of heating the leaf in ethanol in step 3.

Describe the experimental steps a student should take before performing the starch test to demonstrate that each of the following factors is required for photosynthesis: (i) light (ii) chlorophyll (iii) carbon dioxide