I think it would be homogeneous and heterogeneous
Half life is the time that it takes for half of the original value of some amount of a radioactive element to decay.
We have the following equation representing the half-life decay:

A is the resulting amount after t time
Ao is the initial amount = 50 mg
t= Elapsed time
t half is the half-life of the substance = 14.3 days
We replace the know values into the equation to have an exponential decay function for a 50mg sample

That would be the answer for a)
To know the P-32 remaining after 84 days we have to replace this value in the equation:

So, after 84 days the P-32 remaining will be 0.85 mg
Answer: 700 has one significant figure which is 7.
Explanation: These are some rules for significant figures
•All non-zero digits are significant: 1,2,3,4,5,6,7,8,9
•Zero between non-zero digits are significant: They are three significant figures in 203.
•Leading zeros are not significant: There are two significant figures in 0.56.
•Trailing zero to the right of decimal are significant. There are four significant figures in 62.00
•Trailing zeros in a whole number with the decimal shown are significant: This makes "700." three significant figures.
•Trailing zeros in a whole number with no decimal shown are not significant: This makes 700 one significant figure.
Gasoline contains C and H atoms. During combustion, the carbon (C) from the fuel combines with oxygen (O2) from the air to produce carbon dioxide (CO2).
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O.
Combustion reactions release large amounts of heat. They have negative enthalpy. A negative enthalpy represents an exothermic reaction, releasing heat. This reaction is spontaneous and exothermic, since we can obtain energy from the reaction; the ΔG (free energy) is negative (So 1 is true).
ΔG < 0, so the free energy of the system decreases with the reaction. Remember that when there is a negative ΔG the reaction goes from higher free energy to lower free energy, like in this case.