Modern periodic law states that properties of elements are periodic functions of their:
A. Atomic masses
B. Mass numbers
C. Atomic numbers
D. Number of isotopes
Answer: Option C
Solution (By JKExamLibrary)
Modern periodic law: The physical and chemical properties of elements are periodic functions of their atomic numbers. This was established by Moseley. Mendeleev's periodic law was based on atomic masses. Atomic number (Z) determines electronic configuration, which determines chemical behavior. Mass numbers vary with isotopes.
Consider the following statements: 1. Biofuels are renewable energy sources. 2. Biodiesel is produced by the transesterification of vegetable oils. Which is/are correct?
Explanation:
Biofuels, such as bioethanol and biodiesel, are derived from recent biological materials (biomass) and can be replenished, making them renewable. Biodiesel is specifically produced through transesterification, a chemical reaction where vegetable oils or animal fats react with an alcohol (like methanol) to form fatty acid methyl esters.
Explanation:
Nitric acid is a strong mineral acid with the chemical formula HNO₃. It is also known as aqua fortis. HCl is hydrochloric acid, H₂SO₄ is sulfuric acid, and H₃PO₄ is phosphoric acid. Nitric acid is widely used in fertilizers and explosives.
Explanation:
Sodium (Na) is a soft, silvery-white alkali metal (Group 1). It is highly reactive, conducts electricity, and is malleable. Sulfur and phosphorus are non-metals; chlorine is a non-metal halogen gas. Sodium is never found free in nature; it is stored under kerosene to prevent reaction with air/moisture. It reacts vigorously with water, producing NaOH and H₂.
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