NPK stands for Nitrogen (N), Phosphorus (P, as P₂O₅), and Potassium (K, as K₂O). These are primary macronutrients essential for plant growth. The numbers on a fertiliser bag (e.g., 10-26-26) indicate the percentage of N, P₂O₅, and K₂O.
Explanation:
J.J. Thomson discovered the electron in 1897 using a cathode ray tube. He showed that cathode rays were composed of negatively charged particles (electrons) that were much lighter than atoms and were a fundamental part of all matter, leading to his plum pudding model.
Explanation:
Saline water (containing NaCl) increases the electrical conductivity of the water, accelerating the electrochemical process of rusting. This is why ships and coastal structures rust faster. Dry air and vacuum have no moisture; pure water without dissolved oxygen slows rusting.
Explanation:
Mendeleev arranged elements in order of increasing atomic mass and grouped elements with similar chemical properties. He left gaps for undiscovered elements like eka-aluminium (gallium) and eka-silicon (germanium), predicting their properties. The modern table uses atomic number as the basis. Mendeleev's table had anomalies like placing Ar (40) before K (39) due to mass order, later resolved by atomic number concept.
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