Atoms of different elements having same mass number are called:
A. Isotones
B. Isotopes
C. Isobars
D. Isomers
Answer: Option C
Solution (By JKExamLibrary)
Isobars: same mass number, different atomic number. Example: ⁴⁰Ar, ⁴⁰Ca. Isotopes: same atomic number, different mass number. Isotones: same number of neutrons. Isomers: same molecular formula, different structure.
Explanation:
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.
Explanation:
Plaster of Paris (CaSO₄·½H₂O) is formed by heating gypsum (CaSO₄·2H₂O) at 373 K (100°C). This causes it to lose 1.5 molecules of water per formula unit. If heated significantly above 473 K, it loses all water and forms dead burnt plaster (anhydrous CaSO₄), which cannot set with water.
Explanation:
Teflon (Polytetrafluoroethylene or PTFE) is used as a non-stick coating for cookware because of its extreme chemical inertness, high heat resistance, and low friction coefficient. Polythene and PVC melt at lower temperatures, and Bakelite is a thermosetting plastic used for electrical switches.
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