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August 30, 2014

Search: Radioactivity

Number of results: 70

Chemistry
What are the various uses of radioactivity in healthcare? What are the future trends in healthcare with respect to the use of radioactivity?
February 19, 2012 by Nikki

chemistry
What are the various uses of radioactivity in healthcare? What are the future trends in healthcare with respect to the use of radioactivity?
April 19, 2012 by Anonymous

Chemistry please help!
A Cesium 137 sample has a measured radioactivity of 50 microcuries.Cesium 137 has a half-life of 30 years. How long will it take this sample to be reduced to a residual radioactivity of 6.25 microcuries? Is there a formula to calculate half life?
February 9, 2008 by Mary

Radioactivity
When first discovered alpha, beta, and gamma radioactivity were referred to as alpha rays, beta rays, and gamma rays. Now we refer to alpha particles and beta particles, but still use the term gamma rays. What type of particles are alpha and beta commonly known as? What type ...
June 2, 2009 by Lana

ANYBODY KNOW..
does anybody knowq any websites that has qustions about half lives (radioactivity)? Here is a fact sheet. I don't know if it is what you are looking for or not. If you have a question about radioactivity, post it here and I'm sure someone will be able to answer it. http://web....
January 20, 2007 by Mallory

Astronomy
Two bodies with equal masses orbit the Sun in a circular orbit. If the radii of the two orbits are the same then following is true: a) The orbital period of the two bodies is the same because their masses are the same. b) Their orbital period of the two cannot be the same ...
February 11, 2009 by Alex

chemistry
What is the half-life of an isotope if it decays to 12.5% of its radioactivity in 18 minutes?
September 14, 2010 by fatin

Science
Is it true that the atomic bomb couldn't exist without radioactivity?
March 12, 2013 by Stephanie

science
1. What was henri becquerel studying when he accidentally discovered radioactivity?
May 13, 2014 by Sarr3

science
Explain why radioactivity can be used as a "clock" to measure the march of geologic time.
July 11, 2014 by duane

Math
How long will it take for a 1 g sample of Polonium 210 to lose all but 1/28 of its radioactivity if the half-life is 140 d?
August 1, 2011 by Kate

Math
How long will it take for a 1 g sample of Polonium 210 to lose all but 1/28 of its radioactivity if the half-life is 140 d?
August 1, 2011 by Kate

Chemistry
What is the spontaneous disintegration in which two particles and/or electromagnetic radiation are emitted? would it be radioactivity, nuclear energy, fission or fusion? Thank you
April 29, 2010 by Julie

Physics
“Strontium-90 is a pure beta source.” How could a physicist test this statement? I am stuck on this one, but I was thinking through measurement of radioactivity.
August 30, 2013 by Charles

Physical Science
I'm working on the "Introduction to radioactivity and half-life experiment". It's harder than I thought. Any references that you know of that might make this easier to understand?
November 13, 2007 by Tawanza

Radioactivity
The mass number of an atom undergoing beta decay doesn't change. However the daughter nucleus is a different element than the parent. Explain how this is possible
April 14, 2014 by Anonymous

Chemistry
What are the various uses of radioactivity in healthcare? What are the future trends in healthcare with respect to the use of radioactivitiy?
August 28, 2011 by ROCKY

chemistry
The half life of phosphorus -32 is 14.3 days. What percentage of an original samples radioactivity remains after 57.2 days?
May 7, 2012 by matt

Chem
The only stable isotope of fluorine is fluorine-19. Predict possible modes of decay for fluorine-21, fluorine-18, and fluorine-17. Would it just be alpha-particle production, beta-particle production, gamma-ray production, and positron production for all of them? How do i know...
March 25, 2007 by Steve

Radioactivity
Thompson assumed that the amount of positive charge and negative charge in an atom was equal. Was this a reasonable assumption? I really do not understand this.
October 31, 2010 by Anonymous

algebra
Scientists can determine the age of ancient objects by a method called radio carbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope 14C of carbon with a half-life of about 5710 years. Vegetation absorbs carbon dioxide ...
March 7, 2013 by Emily

Physics check
List the three types of radioactivity by increasing ability to penetrate matter. 1 gamma rays 2 beta rays 3 alpha rays ?
April 17, 2008 by Bev

math
How long will it take a given quantity of carbon-14 to lose 99.9% of its radioactivity if the half life is 5730 years? The formula I have been given is Q=ae^rt This is using log and ln functions.
April 25, 2011 by Niki

Chem
Radioactive 24Na with a half-life of 14.8 hours is injected into an animal in a tracer experiment. How many hours will it take for the radioactivity to fall to 12.5% of its original intensity? I am confused on what number to start with
August 27, 2013 by Colby

Radioactivity
A bone fragment has lost 75% of its original carbon-14. What is the age of the bone fragment? My answer is about 11 000 years but I don't know if its right
April 21, 2014 by Aditya

Science radioactivity
why are alpha and beta radiation referred to as particles while gamma radiation is referred to as rays?
April 14, 2014 by Anonymous

Physics
A friend has journeyed to the mountain foothills to escape the effects of radioactivity altogether. While bathing in the warmth of a natural hot spring, she wonders aloud how the spring gets its heat. What do you tell her?
April 17, 2008 by Chad

Radioactivity-to science tutors
Thompson assumed that the amount of positive charge and negative charge in an atom was equal. Was this a reasonable assumption? I really do not understand this. I tried looking up on the site, but information there wasn't so clarified.
November 1, 2010 by Anonymous

Radioactivity or science
A radioactive isotope source has a mass of 120ug. If the isotope had a half life of 20s, what would be the mass if the isotope after 2 mins?
April 21, 2014 by Jannet

Radioactivity
How are the terms "activity" and "becquerel" related? A radioactive isotope source has a mass of 120 g. If the isotope has a half life of 20 secs what would be the mass of the isotope in 2 mins?
April 16, 2014 by Anonymous

physics
A building has become accidentally contaminated with radioactivity. The longest-lived material in the building is strontium-90. (The atomic mass of Sr is 89.9077 u.) If the building initially contained 4.8 kg of this substance and the safe level is less than 10.0 counts/min, ...
June 3, 2012 by andrew

Radioactivity
If you were trying to design the most effective nuclear fission reactor possible, what ratio of U-235 to U-238 would you want? Explain why What happens to the reaction as the proportion of U-238 nuclei increases? Explain why this happens.
April 23, 2014 by Hassina

Calculus-Modeling Equations
An unknown radioactive element decays into non-radioactive substances. In 420 days the radioactivity of a sample decreases by 39 percent. 1.What is the half-life of the element? 2.How long will it take for a sample of 100 mg to decay to 46 mg?
March 6, 2009 by Kim

Science-Physics
One of the things that helped our understanding of radioactivity was the discovery of the electron in 1897. The 100th anniversary of this important discovery was celebrated widely in 1997. Explain why more people were aware of the 100th anniversary than of the original discovery.
May 28, 2012 by Beth

chem
Cobalt-60 is a strong gamma emitter that has a half-life of 5.26 yr. The cobalt-60 in a radiotherapy unit must be replaced when its radioactivity falls to 75% of the original sample. If an original sample was purchased in October 2005, when will it be necessary to replace the ...
September 5, 2012 by hannah

physics-Radioactivity
1) The number of radioactive nuclei in a particular sample decreases over a period of 15 days to one-seventeenth the original number. What is the half-life (in days) of these nuclei? 2) What is the activity of a sample of 14C that contains 1.22E+21 nuclei?
April 18, 2008 by Sandhya

Exponential Growth and Decay
Doctors use iodine-131 to treat some forms of cancer. The half-life of iodine-131 is 8 days. A patient receives a treatment of 12 millicuries. A millicurie is a unit of radioactivity. How much iodine-131 remains in the patient 16 days later?
January 30, 2014 by Anonymous

Bio
A biologist was experimenting with a corn plant that had previously incorporated radioactive carbon into starch stored in its cells. She measured the radioactivity present in the following compounds: Sugar extracted from the plant CO2 producd by the plant Alcohol, if produced ...
November 19, 2009 by Trishia

math
An unknown radioactive element decays into non-radioactive substances. In 100 days the radioactivity of a sample decreases by 64 percent. a)(a) What is the half-life of the element? half-life: b)How long will it take for a sample of 100 mg to decay to 51 mg? time needed:
May 18, 2013 by Rachel

Math
Please show me how to solve: Doctors can use radioactive iodine to treat some forms of cancer. The half-life of iodine - 131 is 8 days. A patient receives a treatment of 12 millicuries of iodine - 131. (A mullicurie is a unit of radioactivity.) How much iodine - 131 remains in...
January 22, 2012 by Jane

Chemistry
The half life of U238 is 4.5 x 10^9 yr. A sample of rock of 1.6 g produces 29 dis/sec. Assuming all radioactivity is due to U238 find percent by mass of U 238. I have tried ln(t)/ln(0)= -kt and still cannot get the answer What I get is A) 4.5x10^9 x365x60x60x24=1.419x10^17 for...
September 22, 2013 by Nancy

physics
Although most natural potassium nuclei are stable 39K (93.3%) or 41K (6.7%) nuclei, about 0.0117% are radioactive 40K nuclei, which have a half-life of 1.26 billion years. If you were worried about 40K radioactivity and wanted to wait for 97 % of the 40K in the environment to ...
June 6, 2013 by Anonymous

Chemistry (Dr.Bob222)
The half-life of P-32 is 14 days. How long after a sample is delivered can a laboratory wait to use a sample in an experiment if they need at least 10 percent of the original radioactivity? I need help on how to set up this problem. What is the general equation to use for a ...
November 7, 2013 by K

maths
Choose three options which are examples of exponential growth or decay. A) The number in the sequence 2,6,24,120,720…… B) The amount of money in a bank account which earns compound interest. C) The radioactivity of a sample of a radioactive isotope. D) The savings of a person ...
April 19, 2007 by katie

English
I am having trouble writing a topical outline and expanding it to a sentence for this paper: Marie Curie is best known as the discoverer of the radioactive elements polonium and radium, and is the first person to earn the honor of two Nobel prizes. Her work not only influenced...
May 3, 2009 by Erin

Science
Three light beams encounter a medium. One light ray is reflected, while the other two are absorbed. How can the medium be described? Transparent Translucent Opaque or Clear In satellite communication, does the satellite... Receive radio signals Prevent radio signals Send radio...
November 30, 2013 by Tooler

sceince
hree light beams encounter a medium. One light ray is reflected, while the other two are absorbed. How can the medium be described? Transparent Translucent Opaque or Clear In satellite communication, does the satellite... Receive radio signals Prevent radio signals Send radio ...
May 16, 2014 by jjk

Radioactivity
Beryllium-7 has a half-life of 53 D. A sample was observed for one minute and there were 26,880 decays. a.) what is the activity level of the sample? b.) what will the activity level of the sample be after 265 d? c.) after how many days will be activity level of the sample be ...
April 17, 2014 by Samaira

geological radioactivity
What ihe basis for the determination of Uranium 238-Lead radiometric date of 1120 ma for granite Wouldn't it be the ratio of U238 and lead in the granite? I do not think so, i have actually answer the question explaing it in words but i am not sure of it as the question is ...
March 28, 2007 by bonita

Radioactivity
1. A granite rock is thought to be about 2 billion years old. why is it not possible to determine the age of the Rock using carbon-14 dating? 2. A hair sample has 80% of its original carbon-14 present. what is the age of the sample? 3. A bone fragment has lost 75% of its ...
April 17, 2014 by Anonymous

physics
A building has become accidentally contaminated with radioactivity. THe longest lived material in the building is strontium-90 (atomic mass of 90 Sr 38 is 89.9077). If the building initially contained 5.0kg of this subtstance and the safe level is less than 10.0 counts/min, ...
February 16, 2007 by soojung

Genetics
The following is pulse-chase experiment was performed as in Okazaki’s experiment, but in an organism as follows (all other as in regular replication): • One linear chromosome • 2 origins of replication spaced 50Kb apart, one firing at t=0 and one in t=10 min. • Genome ...
October 11, 2013 by John

Physics
About 5.12 x 104 m above Earth's surface, the atmosphere is sufficiently ionized that it behaves as a conductor. The Earth and the ionosphere form a giant spherical capacitor, with the lower atmosphere acting as a leaky dielectric. Find the capacitance C of the Earth-...
February 16, 2012 by jason

Radioactivity
1) An old wooden tool is found to contain only 11.9 percent of 14C that a sample of fresh wood would. How many years old is the tool? 2) A specimen taken from the wrappings of a mummy contains 7.02 g of carbon and has an activity of 1.34 Bq. How old is the mummy? Determine its...
April 19, 2008 by Sandhya

Ununhexium/atoms
I don't understand, according to the periodic table at web elements; An isotope of Element 116 (292Uuh) was identified in the reaction of 248Cm with 48Ca. It is very shortlived and decomposes to a known isotope of element 114, 288114Uuq. How can it be that ununhexium is ...
February 3, 2007 by Shove

Chemistry - radioactivity
Hello Dr.Bob. Could you check my work please? I'm not sure if I'm right in how I solved this problem. Which of the following nuclides are most likely to decay via beta decay? A) I-131 B) Pb-206 C) F-18 D) Zr-90 E) Ar-40 I know that nuclides undergo beta decay when they are too...
April 19, 2013 by Constantine

Urgent Science!!!
1. Which of the following is NOT a fossil? (1 point) outline of a fern found in a rock petrified wood in the desert baby mammoth found in a glacier old stone tools found in a cave 2. _____ is based on the idea that younger rock layers are deposited on top of older rock layers ...
January 17, 2013 by plz help

Plutonium decay
The amount A(gms) of radioactive plutonium remaining in a 20gm sample after t days is given by: A = 20 * (1/2)^t/140 At what rate is the plutonium decaying when t = 2 days. I think you need to find dA/dt and evaluate it at t=2 This should be a fairly straight forward ...
October 20, 2006 by Jen

Science Lab -Half-Life of Popcorn
When a radioactive sample decays, there is one less parent nuclei and one more daughter nuclei. As this decay process continues, the number parent nuclei decreases and the number of daughter nuclei increases. Eventually there are no parent nuclei increases. Eventually there ...
October 29, 2010 by Anonymous

Science Please Help Me
1.A weatherman reports, “The storm waves are about 2 meters high and about 35 meters apart.” What properties of waves is the reporter describing? (1 point) A.frequency and wavelength B.wavelength and wave speed C.amplitude and wavelength D.amplitude and frequency 2. Soundproof...
June 3, 2014 by Sarr3

I need help..
1. Diarrhea can be caused by a change in diet and different minerals in the water. True False 2. Fusion produces less radioactivity than fission. True False 3. Wise travelers eat only cooked vegetables in underdeveloped areas. True False 4. The kilogram is the basic unit of ...
January 7, 2013 by Morgan Stevenson

Will somebody help me please?
1. Diarrhea can be caused by a change in diet and different minerals in the water. True False 2. Fusion produces less radioactivity than fission. True False 3. Wise travelers eat only cooked vegetables in underdeveloped areas. True False 4. The kilogram is the basic unit of ...
January 8, 2013 by Morgan Stevenson

Please guys. Help me out.
1. Diarrhea can be caused by a change in diet and different minerals in the water. True False 2. Fusion produces less radioactivity than fission. True False 3. Wise travelers eat only cooked vegetables in underdeveloped areas. True False 4. The kilogram is the basic unit of ...
January 7, 2013 by Morgan Stevenson

Science Somebody Help Me Please..I have a deadline
1. Diarrhea can be caused by a change in diet and different minerals in the water. True False 2. Fusion produces less radioactivity than fission. True False 3. Wise travelers eat only cooked vegetables in underdeveloped areas. True False 4. The kilogram is the basic unit of ...
January 7, 2013 by Morgan S

Chemistry
1. Which of the following is one way to prevent the corrosion of iron? A. Paint exposed iron parts with protective paint. B. Protect the iron from polluted air. C. Add carbon to the iron. D. Let the iron develop a natural coat of carbonate. 2. The source of the sun's heat is A...
October 3, 2013 by StarBuddy

Please CHECK thanks
Please check and tell me what I got wrong and let me know the correct answer for the problem. Thanks. 1. Diarrhea can be caused by a change in diet and different minerals in the water. True (yes) False 2. Fusion produces less radioactivity than fission. True False (yes) 3. ...
January 9, 2013 by Morgan Stevenson

Somebody check this plz..and thanks.
Please check and tell me what I got wrong and let me know the correct answer for the problem. Thanks. 1. Diarrhea can be caused by a change in diet and different minerals in the water. True (yes) False 2. Fusion produces less radioactivity than fission. True False (yes) 3. ...
January 9, 2013 by Morgan Stevenson

chemistry
. Which of the following will result in a chemical change? A. Melting ice to obtain water B. Evaporating alcohol into vapor C. Drying wood in a shed D. Burning coal in a furnace 2. A salt is obtained as a reaction between A. a nonmetal and a metal. B. a base and water. C. an ...
July 2, 2013 by smith

DR BOB - Chemistry Question 4 a - d
a. State the atomic number of ununhexium and give the full symbol for the isotope ununhexium. b. Give the period and the group of the periodic table in which you would expect to find ununhexium, explaining how you arrived at your conclusions. Further name one other chemical ...
February 17, 2007 by Mark jones

chemistry
me again! got a question that really is trying! the isotope of ununhexium Uuh and it undergoes a succession of seven a-decay reactions. I need to find out what the final isotope would be as a result. And is the final product a lanthanide, an actinide, a transition element or a...
February 6, 2007 by bertie

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