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Question- A) You is using a Geiger counter to measure the activity of a radioactive substance over the course of several minutes. If the reading of 400. Counts has diminished to 100. Counts after 62.6 minutes what is the half-life of this substance?
B) An unknown radioactive substance has a half-life of 3.20 hours. If 41.9g of the substance is currently present, what mass A0 was present 8.00 hours ago?
C) 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 45.0% of an Am-241 sample to decay?
D) A fossil was analyzed and determined to have a carbon-14 level that is 20% that of living organisms. The half-life of C-14 is 5730 years. How old is the fossil?
Here is the problem which I am struggling on, please help me
For the reaction:-2 HCl + Na2CO3 - 2 NaCl + H2O + CO2 ,179.2 liters of CO2 is collected at STP.
determine the errors if any with each galvanic cell set-up when the anode is on the left. select all that
Why would it be more appropriate to put the elements La and Ac in the bottom two periods and put Lu and Lr in the transition metals? Why don't we see the use of any sublevels higher than the f sublevel?
An aqueous solution of KNO3 has a molal concentration of 1.099 mol kg-1. Its density is 1.0630 g mL-1. Calculate the molar concentration of KNO3.
Diet coke Chemistry, You drink a 500 ml bottle of Diet Coke, which has 0 calories. The Diet Coke was chilled to 7 degrees C before you drank it. Approximately how much heat energy is drawn from your body to warm this 500 ml of Diet Coke up to your..
consider the reaction CO2+H2=CO+H2O.The equilibrium concentrations are [CO]= 0.050M, [H2]=0.045M, [CO2]=0.086M, and [H2O]= 0.040M. Calculate K .
the mineral is pyroxene.1. recalculate the analysis into chemical formula.the formula should show the atoms of each
It is recommended that we drink 8 glasses of water a day. Each glass of water weighs 240grams. If the human body contains 1.00x10^12 cells and each cell is to get an equal amount of water, how many molecules of water does each cell get each day
which of the following atoms with the specified electronic configuration would have the lowest first ionization energy? (a) (He)2s^2 2p^3 (b) (ne) 3s^2 3p^4 (c) [Xe]6s^1 (d) [Xe]6s^2 4f^14 5d^10 6p^1
Substance A has a greater molar mass then substance B. Both are nonelectrolytes. If 50 g of substance A are dissolved in 250 g of water in one beaker
Predict the rate of change in the concentration of N2O over this time interval. In other words, what is dt [N2O]/ dt?
what minimum mass of succimer in is needed to bind all of the lead in a patients bloodstream? assume that patient
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