Nitric acid (HNO3) is historically known as Aqua Fortis, which translates to 'strong water' in Latin. This name was given by early alchemists due to its ability to dissolve almost all metals, including silver, which was not dissolved by other known acids at the time.
Explanation:
Dmitri Mendeleev proposed the periodic law based on atomic mass. However, anomalies arose. In 1913, Henry Moseley discovered that the atomic number (number of protons) is the fundamental property. He proposed the modern periodic law: the properties of elements are periodic functions of their atomic numbers.
Explanation:
High-concentration H₂O₂ (e.g., 80-90%) decomposes rapidly in the presence of a catalyst to produce superheated steam and oxygen: 2H₂O₂ → 2H₂O + O₂ + heat. This generates high-pressure gas used for propulsion (monopropellant) or as oxidizer in bipropellant systems. It is not a fuel; it provides oxygen for combustion. It must be handled carefully due to instability.
Explanation:
Teflon (PTFE) has a very low coefficient of friction and surface energy because the fluorine atoms form a protective shield around the carbon backbone, making it difficult for other substances to adhere. This is not due to polarity (C-F bonds are polar but the molecule overall is non-polar due to symmetry). It is extremely inert, resisting most chemicals.
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