5-10-5 fertilisers mean that they contain

ANS:A - 5, 10, 5% respectively of N₂, P₂O₅ and K₂O.

The notation "5-10-5" used for fertilizers indicates the relative percentages of three essential nutrients they contain: nitrogen (N), phosphorus (P), and potassium (K). These percentages are represented as the percent of nitrogen, phosphorus pentoxide (P2O5), and potassium oxide (K2O) respectively. So, when you see "5-10-5" on a fertilizer label, it means:

• 5% of the total weight of the fertilizer is nitrogen (N).
• 10% of the total weight of the fertilizer is phosphorus pentoxide (P2O5). The phosphorus is often represented as P2O5, which is the compound formed when phosphorus is oxidized.
• 5% of the total weight of the fertilizer is potassium oxide (K2O).

These three nutrients, N-P2O5-K2O, are essential for plant growth and development. Nitrogen supports vegetative growth, phosphorus is vital for root development and flowering, and potassium contributes to overall plant health, stress tolerance, and fruit production. This notation system provides a quick way for gardeners and farmers to understand the nutrient composition of fertilizers and select the appropriate one for their specific needs.