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: if doing it on ck-12 the answer is 40.1
Explanation:
A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity.
Examples of chemical changes are burning, cooking, rusting, and rotting.
Examples of physical changes are boiling, melting, freezing, and shredding.
1 molecule of glucose contains 6 atoms of C, 12 atoms of H , and 6 atoms of 0.1 mole of glucose contains 6 moles of C atoms , 12 moles of H atoms , and 6 moles of O atoms .
Full Question:
Ammonia chemically reacts with oxygen gas to produce nitric oxide and water. What mass of water is produced by the reaction of 7.7g of ammonia?
Be sure your answer has the correct number of significant digits.
Answer:
12.23g ≈ 12g (2 s.f)
Explanation:
Ammonia chemically reacts with oxygen gas to produce nitric oxide and water. The balanced chemical reaction is given as:
4 NH3 + 5 O2 -------> 4 NO + 6 H2O
From the reaction;
4 mole of ammonia reacts to produce 6 moles of water
From the question;
Moles = mass / molar mass
From the question;
moles of ammonia = mass / molar mass = 7.7 / 17 = 0.4529moles
Number of moles of water produced;
4 = 6
0.4529 = x
x = (0.4529 * 6 ) / 4
x = 0.67935moles
Mass of water = moles * molar mass = 0.67935 * 18 = 12.23g ≈ 12g (2 s.f)