Who proposed the atomic theory of matter, stating that all matter is composed of indivisible atoms?
A. J.J. Thomson
B. John Dalton
C. Ernest Rutherford
D. Dmitri Mendeleev
Answer: Option B
Solution (By JKExamLibrary)
John Dalton proposed the atomic theory in 1803. His theory stated that all matter is made of indivisible and indestructible atoms, atoms of a given element are identical in mass and properties, and compounds are formed by combinations of different atoms in fixed ratios.
Explanation:
Sodium and potassium are highly reactive alkali metals that react vigorously with oxygen and moisture in the air, potentially catching fire. To prevent accidental fires, they are stored immersed in kerosene oil. Magnesium and calcium do not require such extreme storage conditions.
Explanation:
Urea (CO(NH₂)₂) is a nitrogenous fertilizer with the highest nitrogen content (about 46%). Superphosphate provides phosphorus, muriate of potash (KCl) provides potassium, and gypsum (CaSO₄·2H₂O) is a soil conditioner providing calcium and sulfur, not primary NPK nutrients.
Explanation:
Biogas, commonly known as gobar gas in India, is produced by the anaerobic digestion of organic waste (like cattle dung) by methanogenic bacteria. The primary component of biogas is methane (CH4), which typically makes up 50-75% of the gas mixture, along with carbon dioxide and trace gases.
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