Which of the following solvents will best dissolve wax, which is a complex mixture of compounds that mostly are CH3−CH2−CH2−CH2−
CH2—? Structural formulas for molecules (a) (a) Hexane (a) Hexane is a six-carbon zigzag chain, with the terminal carbons single bonded to three Hs and all other Cs to two Hs. Structural formulas for molecules (b) (b) Benzene (b) Benzene is a six-membered ring with carbon as all of its vertices and alternating single and double bonds as the sides. Each carbon is also single bond-ed to H. Structural formulas for molecules (c) (c) Acetone (c) Acetone is a central C double bonded above to O and single bonded right and left, angled down, to CH3. Structural formulas for molecules (d) (d) Carbon tetrachloride (d) Carbon tetrachloride is a central C single bonded to four Cls. Structural formulas for molecules (e) (e) Water
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Answer:
Explanation:
A radioactive isotope is an isotope that undergoes nuclear decay, breaking apart into a smaller nucleus and emitting radiation during the process.
The half-life of an isotope is the amount of time it takes for a certain quantity of a radioactive isotope to halve.
For a radioactive isotope, the amount of substance left after a certain time t is:
(1)
where
is the mass of the substance at time t = 0
m(t) is the mass of the substance at time t
is the half-life of the isotope
In this problem, the isotope is uranium-235, which has a half-life of
We also know that the amount of uranium left in the rock sample is 6.25% of its original value, this means that
Substituting into (1) and solving for t, we can find how much time has passed: