Answer:
a) a0 was 46.2 grams
b) It will take 259 years
c) The fossil is 1845 years old
Explanation:
<em>An unknown radioactive substance has a half-life of 3.20hours . If 46.2g of the substance is currently present, what mass A0 was present 8.00 hours ago?</em>
A = A0 * (1/2)^(t/h)
⇒ with A = the final amount = 46.2 grams
⇒ A0 = the original amount
⇒ t = time = 8 hours
⇒ h = half-life time = 3.2 hours
46.2 = Ao*(1/2)^(8/3.2)
Ao = 261.35 grams
<em>Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 years. How long will it take in years for 34.0% of an Am-241 sample to decay?</em>
t = (ln(0.66))-0.693) * 432 = 259 years
It will take 259 years
<em>A fossil was analyzed and determined to have a carbon-14 level that is 80% that of living organisms. The half-life of C-14 is 5730 years. How old is the fossil?</em>
<em />
t = (ln(0.80))-0.693) * 5730 = 1845
The fossil is 1845 years old
Increased Evaporation/B is correct :p
Element 87 francium have the highest atomic size, so in short the closest element to francium have the high atomic size.
Answer:
ΔPV = -9911 J
Explanation:
The combustion of 1 mole of heptane is:
C₇H₁₆(l) + 11O₂(g) → 7CO₂(g) + 8H₂O(l)
The change in number of moles of gas molecules is:
Δn = 7 moles products - 11 moles reactants = -<em>4 moles</em>
Using ideal gas ΔPV is:
ΔPV = ΔnRT
Where:
Δn is -4mol
R is 8,314472 J/molK
T is 298K
Replacing:
<em>ΔPV = -9911 J</em>
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I hope it helps!
1. Homogeneous substance
2. Homogeneous mixture cannot be separated into their respective constituents similar to elements that cannot be separated into simpler substance (not sure)