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What is a metal replacement reaction

Most materials are not magnetic because their magnetism has worn off. their magnetic domains are arranged randomly. they lack magnetic fields. earth’s heat has destroyed their magnetism.

Use the de broglie's wave equation to find the wavelength of an electron moving at 7.3 × 106 m/s. show your work. note: h = plank's constant (6.62607 x 10-34 j s)