Answer:

Explanation:
Hello,
In this case, we need to remember that for the required time for a radioactive nuclide as radium-226 to decrease to one half its initial amount we are talking about its half-life. Furthermore, the amount of remaining radioactive material as a function of the half-lives is computed as follows:

Therefore, for an initial amount of 100 mg with a half-life of 1590 years, after 1000 years, we have:

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Crush the limestone... it would give more area for the acid to react
Answer:
Nonbonding pairs of electrons.
Explanation:
Both oxygen atoms in the diatomic molecule have two nonbonding pairs. This results in the oxygen molecule having a planar geometric shape. This is because nonbonding pairs repel each other are significant in determining the shape of a molecule.
The equation that relates both energy and wavelength is:

where e is the energy and lambda is the wavelength.
Therefore, as we can see from this equation, the energy of an electromagnetic wave is inversely related to the wavelength of the electromagnetic wave.