Final answer:
A 10kg bag of fertilizer labeled 20-5-10 contains 0.5kg of P2O5, which is the shorthand for the phosphorus content of the fertilizer.
Step-by-step explanation:
The question is about how much phosphorus is in a 10kg bag of fertilizer labeled 20-5-10. This label represents an NPK rating, which denotes the percentages of nitrogen (N), phosphorus (P), and potassium (K) in the fertilizer. The second number in the NPK rating represents the percentage of P2O5, which is a conventional shorthand for the phosphorus content in a fertilizer. To calculate the amount of phosphorus, you would take 5% (the phosphorus percentage) of the total weight of the bag. Therefore, in a 10kg bag, 5% of phosphorus is 0.05 × 10kg, which equals 0.5kg of P2O5. This is the conventional representation, and actual phosphorus content will be less since P2O5 contains oxygen as well as phosphorus.