Numbers 1-4 are which element is used to identify four different elements in the
ID: 998782 • Letter: N
Question
Numbers 1-4 are which element is used to identify four different elements in the periodic table. Of these, most likely to have +3 charge when it forms an ion? The statement "A chemical reaction never creates products that weigh more or less than the reactants" is based on more than three centuries of experimental observation. The statement is an example of a law. a hypothesis. a datum, a theory. Which of these forms of electromagnetic radiation from the Sun has the lowest energy and therefore the least potential for damage to biological systems?Explanation / Answer
21) b) 2 - 4th period & IB grup - Selenium -21Se forms +3 charge since it has 4s23d1 outermost electronic configuration, it easily loses three electrons from valency shell.
22) a) a law is correct answer. The statement is a law because it describes a pattern or a relationship in a large amount of experimental data. It isn't a datum because it doesn't represent a single observation; it is a conclusion summarizing many observations. It isn't a theory because it isn't an explanation. It isn't a hypothesis because it isn't tentative.
23) a) infrared is correct answer. Because sun never emits radio waves. The lowest energy always associates with longer wavelength, out of infrared, UV and Visible only infrared has longer wavelength implies lowest energy.
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