Radioactive material obeys 1st order decay kinetics,
For 1st order reaction, we have
k =

where, k = rate constant of reaction
Given: Initial conc. 100, Final conc. = 6.25, t = 18.9 hours
∴ k =

= 0.1467 hours^(-1)
Now, for 1st order reactions: half life =

= 4.723 hours.
Answer:
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Explanation: this was easy for me
It is 4/10 of moles is this ane halp?
Answer:
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Answer:
0.00007975 mole
Explanation:
Number of moles can be calculated as; mass of solute/volume of solvent or concentration of solution x volume of that solution.
In this case:
Concentration of solution = 1.45 M
Mass of solvent (water in this case) = 55.0 mg
55.0 mg of water is equivalent to 0.55 ml of water.
Therefore, volume of solution = 0.055 ml
Hence, number of moles of solute = molarity x volume
1.45 x 0.000055 = 0.00007975 mole