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Questions in chemistry

[Done] What is the electron configuration of [tex]Ca^{2+}[/tex]?

[Done] How was nitrogen discovered?

[Done] Which of the following is the best evidence that digestion involves chemical change? A. Time is required to accomplish results. B. The products’ mass equals the reactants’ mass. C. Different compounds are involved. D. New substances are produced.

[Done] Compounds have physical properties that: A. Resemble the physical properties of one of their elements. B. Differ greatly from the properties of all of their elements. C. Resemble the physical properties of all of their elements. D. Differ greatly from the properties of one of their elements.

[Done] As an object’s temperature increases, the rate at which it radiates energy increases.

[Done] What happens to reactant molecules when forming product molecules?

[Done] Hydrogen is a nonmetal, and oxygen is a nonmetal. If these two elements were to bond, they would form a(n) _____.

[Done] If a radioisotope has a half-life of 10 years, how much of the original material would remain after 40 years?

[Done] What is the difference between solid HCl and liquid HCl?

[Done] How many moles of calcium are in a sample of 40 g?