Answer:
5
Explanation:
An atom has the same number of protons and electrons
<u>Answer:</u>
Steep slopes on the contour map are identified using contour lines which are closely spaced.
<u>Explanation:</u>
Contour map also known as topographic maps are used to represent the three-dimensional portion of the earth’s surface in two-dimensional space. This map is used to represent the surface of the land such as steep, slopes, valleys. The contour maps are used in geological studies to understand the configuration of the earth's surface. Terms like map scale, vertical scale, contour lines are used on the contour map. Elevations are represented using contour lines. Contour lines placed very close to each represent the steep slopes and contour lines that are spaced farther away from each other represent the gentle slopes.
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 book<span> documented the detrimental effects on the environment—particularly on birds—of the indiscriminate use of pesticides. -A</span>
