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:
I think it's gold but I'm not sure, sorry
Explanation:
good luck tho :)
Widespread distribution of Permo-Carboniferous glacial sediments in South America, Africa, Madagascar, Arabia, India, Antarctica and Australia was one of the major pieces of evidence for the theory of continental drift.
Here we have to get the 
of the reaction at 520 K temperature.
The of the reaction is 1.705 atm
We know the relation between and 
is 
, where = The equilibrium constant of the reaction in terms of partial pressure, = The equilibrium constant of the reaction in terms of concentration and N = number of moles of gaseous products - Number of moles of gaseous reactants.
Now in this reaction, PCl₃ + Cl₂ ⇄ PCl₅
Thus number of moles of gaseous product is 1, and number of moles of gaseous reactants are 2. Thus N = |1 - 2| = 1 mole
The given value of is 4.0×10⁻²
The molar gas constant, R = 0.082 L. Atm. mol⁻¹. K⁻¹ and temperature, T = 520 K.
On plugging the values in the equation we get,
Or, = 1.705 atm
Thus, the of the reaction is 1.705 atm
