1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
arlik [135]
3 years ago
15

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?Express your answer with the appropriate units.
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?

Express your answer with the appropriate units.

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?

Express your answer with the appropriate units.
Chemistry
1 answer:
iogann1982 [59]3 years ago
7 0

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

You might be interested in
Based on the data given, which factor had the greatest effect on the behavior of the gas
Pepsi [2]
Do you have the picture of the data?
6 0
3 years ago
An iron loses electrons. State the type of charge it will end up with
erastova [34]

Answer:

Most atoms do not have eight electrons in their valence electron shell. Some atoms have only a few electrons in their outer shell, while some atoms lack only one or two electrons to have an octet. In cases where an atom has three or fewer valence electrons, the atom may lose those valence electrons quite easily until what remains is a lower shell that contains an octet. Atoms that lose electrons acquire a positive charge as a result because they are left with fewer negatively charged electrons to balance the positive charges of the protons in the nucleus. Positively charged ions are called cations. Most metals become cations when they make ionic

4 0
2 years ago
What is the answer helpnme plz
kykrilka [37]
MgH2 + 2 H2O → Mg(OH)2 + 2 H2
8 0
2 years ago
Which of the following is a mixture of substances?
Stels [109]

Answer:

the answer is c

b/c contain more than one element

7 0
3 years ago
Explain how scientists use geologic time to determine the age of land forms.
valentina_108 [34]
I am sorry i wish i could help you but i dont know the answer either.
5 0
3 years ago
Other questions:
  • What happens when a penny is dropped from a height of 20 meters?
    14·1 answer
  • Here is the science paper
    6·1 answer
  • How many moles of carbon dioxide gas, co2, are there in 2.94 l of this gas at stp
    13·2 answers
  • Describe the particles that make up a pure substance
    10·1 answer
  • how many calories of energy are given off to lower the temperature of 100.0g of iron from 150.0°C to 35.0°C?
    8·1 answer
  • rank the following elements in order of increasing atomic size sodium, hydrogen, carbon and beryllium
    13·1 answer
  • According to the graph, which statement is correct?
    9·2 answers
  • What two particles must a substance particles exhibit in order to conduct electricity
    5·1 answer
  • What’s this answer help me out
    11·1 answer
  • Which gas law states that the volume of gas is directly proportional to its temperature
    15·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!