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
The question is incomplete, the complete question is;
A molecule that contains three identical polar bonds to the central atom will be ________.
nonpolar if the geometry is planar triangular
polar in all cases
nonpolar in all cases
impossible to tell the polarity
either polar or nonpolar depending on the identity of the atoms bonded to the central atom
Answer:
Nonpolar if the geometry is planar triangular
Explanation:
The polarity of molecules depends both on the polarity of individual bonds in the molecule as well as the overall dipole moment of the molecule. We must remember that dipole moment is a vector quantity hence direction of the resultant vector is very important.
Now, if i have a molecule that contains three identical polar bonds, a planar triangular geometry means that the molecule is symmetrical and will have an overall dipole moment of zero. Hence the molecule is nonpolar.
