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.
I think c is the right answer
<u>Answer:</u> The isotope produced after the transmutation process of Cf-249 and C-12 is 
<u>Explanation:</u>
Transmutation is defined as the process where one chemical isotope gets converted to another chemical isotope. The number of protons or neutrons in the isotope gets changed.
The chemical equation for the reaction of Californium-249 nucleus with Carbon-12 nucleus follows:

In a nuclear reaction, the total mass and total atomic number remains the same.
<u>To calculate A:</u>
Total mass on reactant side = total mass on product side
249 + 12 = A + 4
A = 257
<u>To calculate Z:</u>
Total atomic number on reactant side = total atomic number on product side
98 + 6 = Z + 0
Z = 104
Hence, the isotope produced after the transmutation process of Cf-249 and C-12 is 
Answer:
c
Explanation:
thw observation of water that is added
<span>Alfred Wegener was the first one to propose the idea of moving continents as a scientific hypothesis
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