Question

The number of absorbed CO$_2$ and water molecules to produce 180 g of glucose in plants are:

• A. 264 g and 108 g
• B. 264 g and 193 g
• C. 271 g and 108 g
• D. 193 g and 108 g

Hint:

For every 180 g of glucose made in photosynthesis, plants absorb 264 g of CO₂ and 108 g of water.

Answer 1

The Correct Option is A

The balanced photosynthesis equation is: \[ 6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2 \] This tells us: - 6 moles of CO$_2$ (molar mass = 44 g/mol)
- 6 moles of H$_2$O (molar mass = 18 g/mol)
- produces 1 mole of glucose (C$_6$H$_{12}$O$_6$, molar mass = 180 g/mol)
So to produce 180 g of glucose:
- CO$_2$ required = \(6 \times 44 = 264\) g
- H$_2$O required = \(6 \times 18 = 108\) g
Hence, to produce 180 g of glucose, plants need 264 g of CO₂ and 108 g of water.

Answer 2

The number of absorbed CO₂ and water molecules to produce 180 g of glucose in plants are:

The photosynthesis reaction for glucose synthesis is:
6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

This means that to produce 1 molecule of glucose (C₆H₁₂O₆), a plant absorbs 6 molecules of carbon dioxide and 6 molecules of water.

- Molecular mass of glucose (C₆H₁₂O₆) = 180 g/mol
- Molecular mass of CO₂ = 44 g/mol
- Molecular mass of H₂O = 18 g/mol

To produce 180 g of glucose:
- CO₂ required = 6 × 44 = 264 g
- H₂O required = 6 × 18 = 108 g

Therefore, 264 g of carbon dioxide and 108 g of water molecules are absorbed to produce 180 g of glucose.

Correct Answer: 264 g and 108 g