<span>Answers are:
-4 for C in CH4, because carbon has greater electronegativity than hydrogen and he attracts shared electrons.
</span><span>+4 for C in CO2, because carbon has smaller electronegativity than oxygen.
</span><span>+1 for H in both CH4 and H2O, because hydrogen has amaller electronegativity than both carbon and oxygen.
</span>
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
<u>Answer:</u> The given quantity is a type of length and is measured i the units of meters.
<u>Explanation:</u>
For the given quantity which is 4.8 meters, the unit is meters ans it the unit used to measure the length of an object.
For example: The height of the building is 150 meters. This statement means that the length of the building from the ground is 150 and it is measured in the units of meters.
Hence, the given quantity is a type of length and is measured i the units of meters.
