The half-life of gold-198 is 2.77 days
Given:
mass of gold sample = 200-gram
mass of decay sample = 160 grams
time taken to decay = 6.25 days
To Find:
the half-life of gold-198
Solution: The amount of time it takes to disintegrate by half an initial amount. For a given reaction, a reactant's half-life t1/2 is the time it takes for its concentration to reach a value which is the arithmetic mean of its initial and final (equilibrium) value.
Since Au-198 is 200 g originally and it decays to 160 g, so 40g left
the fraction decay is 40/200 = 0.2
the time base is 6.25 days
ln0.2/6.25 = -0.25
k=ln2/half life therefore half-life = ln2/k = ln2/0.25
half life = 2.77 days
So, half life of gold is 2.77 days
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Answer: 11.2 moles of 
are produced when 5.60 mol of ethane is burned in an excess of oxygen.
Explanation:
The combustion of ethane is represented using balanced chemical equation:
As oxygen is preset in excess, ethane acts as the limiting reagent as it limits the formation of product.
According to stoichiometry :
2 moles of propane produces 4 moles of carbon dioxide
Thus 5.60 moles of propane will produce=
moles of carbon dioxide
Thus 11.2 moles of are produced when 5.60 mol of ethane is burned in an excess of oxygen.
Don’t have a calculator on me but multiply 6.02x10 to the 23rd power by 4.5
The intestines
By the time food has reached the intestines, it has already passed through the gizzard (where it is ground up) and has nutritious pieces absorbed before waste is passed to the excretory system.
