The answer is <span>(3) 3 × 12.4 hours
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To calculate this, we will use two equations:


where:
<span>n - number of half-lives
</span>x - remained amount of the sample, in decimals
<span>

- half-life length
</span>t - total time elapsed.
First, we have to calculate x and n. x is <span>remained amount of the sample, so if at the beginning were 16 grams of potassium-42, and now it remained 2 grams, then x is:
2 grams : x % = 16 grams : 100 %
x = 2 grams </span>× 100 percent ÷ 16 grams
x = 12.5% = 0.125
Thus:
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It is known that the half-life of potassium-42 is 12.36 ≈ 12.4 hours.
Thus:
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</span><span>

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Therefore, it must elapse 3 × 12.4 hours <span>before 16 grams of potassium-42 decays, leaving 2 grams of the original isotope</span>
Answer: B) 2 (as indicated by electron distribution shown), but taking into account the real properties of this element, 4,7,8 also occur (see below).
Explanation:
This is the electron complement/atomic number of ruthenium, which actually has the structure [Kr] 5s1 4d7
Nevertheless, Ru does not form Ru(I) compounds and few Ru(II) compounds (RuCl2, RuBr2, RuI2). It also forms Ru(III)Cl3 and a larger number of Ru(IV) compounds, e.g. RuO2, RuS2. It also forms RuO4
4. <span>The metals that would be able to reduce copper ions in solution would be hydrogen(H), lead(Pb), tin(Sb), nickel(Ni), iron(Fe), zinc(Zn), aluminum(Al), Magnesium(Mg), sodium(Na), calcium(Ca), potassium(K), and lithium(Li).
5. </span>If you had a house with both copper- and zinc-galvanized iron water pipes,zinc would be desirable because <span>A metal that is easily oxidized would rust more readily.</span><span>
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Answer:
Answer is B.
Explanation:
Hydrogen bonds forms when hydrogen atom is attracted towards oxygen atom of other water. A proton is shared by two ion electrons pair in which oxygen atom is partially negatively charged while hydrogen atom is partially positively charged.
I'm not sure but i would say C.storing the heat energy.