How does the atomic structure affect the behavior and properties of an atom? what are the roles of protons and electrons? what are noble gases and why are they the most stable elements?

the electronic configuration determines the physical and chemical properties of an atom

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a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.