Naphthalene balls are used to protect clothes from insects because, when they deteriorate, they create a gas that kills some insects. The naphthalene ball gradually decreases because naphthalene goes through sublimation at room temperature.
Answer:
b. 0.47 moles Ca.
Explanation:
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In this case, since 1 mole of any element contains 6.022x10²³ atoms of the same, it is possible for us to compute the moles in 2.8x10²³ atoms of calcium via the Avogadro's number:
![2.8x10^{23}atomsCa*\frac{1molCa}{6.022x10^{23}atomsCa}\\\\=0.47molCa](https://tex.z-dn.net/?f=2.8x10%5E%7B23%7DatomsCa%2A%5Cfrac%7B1molCa%7D%7B6.022x10%5E%7B23%7DatomsCa%7D%5C%5C%5C%5C%3D0.47molCa)
Therefore, the answer would be b. 0.47 moles Ca.
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Answer: Atomic mass is associated with the number of neutrons and protons that are present in a particular nucleus of an element. Atomic number is usually the number of protons present in an element's nucleus. It is the average weight of an element. It is the total number of nucleons in the atom's nucleus.
Assuming there were errors in atomic masses, Mendeleev placed certain elements not in order of increasing atomic mass so that they could fit into the proper groups (similar elements have similar properties) of his periodic table.
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