Answer:
220.42098 amu
Explanation:
(220 .9 X .7422) + (220 X .0.1278) + (218.1 X 0.13) = 220.42098 amu
These are weighted averages.
So, we will take mass of one and multiply by abundance percentage that is provided and add them together.
In order to calculate the average atomic mass, we have to convert the percentages of abundance to decimals. So, you get
(220 .9 X .7422) + (220 X .0.1278) + (218.1 X 0.13) = 220.42098 amu
<u>Answer:</u> The final equation has hydroxide ions which indicate that the reaction has occurred in a basic medium.
<u>Explanation:</u>
Redox reaction is defined as the reaction in which oxidation and reduction take place simultaneously.
The oxidation reaction is defined as the reaction in which a chemical species loses electrons in a chemical reaction. It occurs when the oxidation number of a species increases.
A reduction reaction is defined as the reaction in which a chemical species gains electrons in a chemical reaction. It occurs when the oxidation number of a species decreases.
The given redox reaction follows:

To balance the given redox reaction in basic medium, there are few steps to be followed:
- Writing the given oxidation and reduction half-reactions for the given equation with the correct number of electrons
Oxidation half-reaction: 
Reduction half-reaction: 
- Multiply each half-reaction by the correct number in order to balance charges for the two half-reactions
Oxidation half-reaction:
( × 3)
Reduction half-reaction:
( × 2)
The half-reactions now become:
Oxidation half-reaction: 
Reduction half-reaction: 
- Add the equations and simplify to get a balanced equation
Overall redox reaction: 
As we can see that in the overall redox reaction, hydroxide ions are released in the solution. Thus, making it a basic solution
.035 gallons equals 0.1324894 L
We are given the following equation:
y = y0 e^-0.0001216 t
where y = 1/5 y0, y0 is the original amount
So solving for time t:
1/5 y0= y0 e^-0.0001216 t
t = 13,235.51 years
So the human died about 13235.5 years ago