Chemistry

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1. Chemistry

   Geologists can estimate the age of rocks by their uranium-238 content. The uranium is incorporated in the rock as it hardens and then decays with first-order kinetics and a half-life of 4.5 billion years. A rock is found to

2. Chemistry(difficult)

   A moon rock collected by a U.S. Apollo mission is estimated to be 3.70 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass of 206Pb per 1.185 g of

3. Science Help Urgent!!!!!

   A particular neutral uranium atom has 92 protons, 143 neutrons, and an atomic mass of 235. How many electons does the atom have? a. 92 b. 143 c. 235 d. 337 Is the answer A?

4. college math

   the half life of Uranium -238 is 4.5 billion years and the age of earth is 4.5 X 109 years. What fraction of Uranium-238 that was present when earth was formed still remains?

1. CHEMISTRY

   The concentration of Pb2+ in a sample of wastewater is to be determined by using gravimetric analysis. To a 100.0-mL sample of the wastewater is added an excess of sodium carbonate, forming the insoluble lead (II) carbonate

2. Math

   Radioactive​ uranium-235 has a​ half-life of about 700 million years. Suppose you find a rock and chemical analysis tells you that only one sixteenth of the​ rock's original​ uranium-235 remains. How old is the​ rock?

3. chemistry

   What mass of lead (ii) trioxonitrate(v) would be required to yield 9g of lead(ii)chloride on the addition of excess sodium chloride(pb=207,N=14,O=16,Na=23,cl=35.5)

4. Atomic Model/Science

   A particular neutral uranium atom has 92 protons,143 neutrons, and an atomic mass of 235. How many electrons does the atom have?

1. chemistry

   A moon rock collected by a U.S. Apollo mission is estimated to be 4.50 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass of 206Pb per 1.150 g of

2. 11th grade

   How many uranium atoms are there in 9.5 g of pure uranium? The mass of one uranium atom is 4 × 10−26 kg

3. Radiometric (Radioactive) Dating

   How old is a sample that contains 125 atoms of U-235 and 375 atoms of Pb-207? ...Given that the half life values on my handout are 713 million years. *I do not even know where to start so could you please explain in steps too?

4. Physics

   In the first step of nuclear fission, a U-235 atom absorbs a neutron and becomes U-236 before becoming unstable and breaking into two smaller atoms and emitting various energies and particles. The mass of the U-235 is 235 amu and

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