Answer:
Left amount of Polonium-210 after 115 days will be 4.5927 microgram
Explanation:
We have given initial mass of Polonium-210 
Decay rate x= 0.502% = 0.00502
Time t = 115 days
We have to find the left amount of Polonium -210 after 115 days
We know that left amount is given by

So left amount of Polonium-210 after 115 days will be 4.5927 microgram
A catalyst decreases the activation energy and increases reaction rate that is needed.
From the given balanced chemical reaction,
C + O2 -> CO2
the mass ratio of the carbon and oxygen that is needed for the reaction is 12:32. Simplifying the ratio gives 3 unit mass C is to 8 unit mass O2. Given 18 g of carbon,
18 g x (32 g oxygen / 12 g carbon) = 48 grams.
For the given product, the ratio of oxygen to carbon dioxide is 32: 44.
72 g CO2 x (32 g O2 / 44 g CO2) = 52.36 grams
Called bioconversion although it can also be referred to as bio transformation