Which element was discovered by Henry Moseley through his X-ray spectra experiments?
A. Proton
B. New way to determine atomic number
C. Neutron
D. Electron
Answer: Option B
Solution (By JKSSB Mock Tests)
Henry Moseley (1913) established the concept of atomic number as the number of protons through X-ray spectra of elements. He showed that atomic number, not atomic mass, is the fundamental property for arranging elements in the periodic table, resolving anomalies in Mendeleev's table. He did not discover a particle but a principle. Modern periodic law is based on atomic number.
Explanation:
Teflon (PTFE) has a very low coefficient of friction and high heat resistance, making it ideal for non-stick coatings. Polystyrene is used in packaging, polyethylene in plastic bags, nylon in textiles and ropes. Teflon's monomer is tetrafluoroethene.
Explanation:
Teflon (PTFE) is an addition polymer of tetrafluoroethene (CF₂=CF₂). The polymer has a linear chain of –CF₂–CF₂– units with high C–F bond strength, making it chemically inert and heat resistant. PVC is polymer of vinyl chloride (CH₂=CHCl). Polyethylene comes from ethylene. Polystyrene from styrene. Teflon is used for non-stick coatings, electrical insulation, and chemical containers.
Explanation:
Boyle's law states that at constant temperature, the volume of a given mass of gas is inversely proportional to pressure: PV = constant. So P ∝ 1/V. Charles' law relates V and T at constant P. Gay-Lussac's law relates P and T at constant V. Boyle's law is used in syringes and scuba diving. Graph of P vs V is a hyperbola; P vs 1/V is a straight line.
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