Which of the following is a correct match of the scientist and the discovery?
A. Rutherford – Nucleus
B. Bohr – Electron
C. J.J. Thomson – Neutron
D. Chadwick – Proton
Answer: Option A
Solution (By JKSSB Mock Tests)
Ernest Rutherford discovered the atomic nucleus through his gold foil experiment (1911). J.J. Thomson discovered the electron (1897). Chadwick discovered the neutron (1932). Bohr proposed the model of the atom with quantized energy levels (1913), not the electron. Rutherford also discovered the proton (1919). Naming discoveries correctly is important for competitive exams.
Explanation:
NPK is a mixed (complex) fertilizer containing nitrogen, phosphorus, and potassium. Urea is a straight nitrogenous fertilizer. Ammonium sulfate is nitrogenous. Superphosphate is phosphatic. Mixed fertilizers supply two or more primary nutrients. They can be granulated or blended. DAP provides N and P, but NPK provides all three.
Explanation:
Mendeleev left gaps and predicted properties of eka-boron (scandium), eka-aluminium (gallium), and eka-silicon (germanium). Germanium was discovered in 1886, its properties matched predictions, confirming the periodic law.
Explanation:
Normal rainwater is slightly acidic with a pH of about 5.6. This is due to the natural dissolution of carbon dioxide from the air into the rain droplets, forming weak carbonic acid (CO₂ + H₂O ⇌ H₂CO₃). Acid rain has a pH lower than 5.6 due to pollutants.
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