3. what is the chemical formula for photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

What the symbols stand for:
CO2 = carbon dioxide
H2O = water
light is required
C6H12O6 = glucose
O2 = oxygen

Photosynthesis is the process plants go through to create its own food. It uses three components: light energy, carbon dioxide, and water. 6 carbon dioxide molecules and 6 water molecules are combined using heat from the light energy to result in 6 oxygen molecules and one molecule of the plant's food-- glucose.

6 carbon dioxide: 6CO2 (the number 2 is a subscript)
6 water: 6H2O (the number 2 is a subscript)
Oxygen: O2 (the number 2 is a subscript)
Glucose: C6H12O6 (numbers 6 and 12 are the subscript)

Combine carbon dioxides with waters :
6CO2 + 6H2O

To combine, light energy is used. Light energy is represented by the arrow:
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Results in glucose and 6 oxygen:
C6H12O6 + 6O2

Combine all parts:
6CO2 + 6H2O > C6H12O6 + 6O2
(Remember to mention light energy is represented by the arrow)