Answer:
- The abundance of 107Ag is 51.5%.
- The abundance of 109Ag is 48.5%.
Explanation:
The <em>average atomic mass</em> of silver can be expressed as:
107.87 = 106.90 * A1 + 108.90 * A2
Where A1 is the abundance of 107Ag and A2 of 109Ag.
Assuming those two isotopes are the only one stables, we can use the equation:
A1 + A2 = 1.0
So now we have a system of two equations with two unknowns, and what's left is algebra.
First we<u> use the second equation to express A1 in terms of A2</u>:
A1 = 1.0 - A2
We <u>replace A1 in the first equation</u>:
107.87 = 106.90 * A1 + 108.90 * A2
107.87 = 106.90 * (1.0-A2) + 108.90 * A2
107.87 = 106.90 - 106.90*A2 + 108.90*A2
107.87 = 106.90 + 2*A2
2*A2 = 0.97
A2 = 0.485
So the abundance of 109Ag is (0.485*100%) 48.5%.
We <u>use the value of A2 to calculate A1 in the second equation</u>:
A1 + A2 = 1.0
A1 + 0.485 = 1.0
A1 = 0.515
So the abundance of 107Ag is 51.5%.
One of the major events is Volcanos etc...
1) Calculate the volume from d = m/V => V = m/d = 2.0*10^-23 g / 1.0*10^14 g/cm^3 = 2.0*10^-9 cm^3
2) Now use the formula of volume for a sphere: V = (4/3)π(r^3) =>
r =∛[3V/(4π)] = ∛[(3*2.0*10^-9 cm^3) / (4π)] = 0.48*10^-3 cm = 4.8*10^-4 cm = 0.00048cm
The answer is; B
Initially, the earth’s atmosphere was mainly filled with carbon dioxide and methane. However, with the evolution of photosynthetic organisms, the composition of the atmosphere changed to be mainly oxygen. This geological time is referred to as the great oxygenation event. The high oxygen levels resulted in oxidation of most the upper lithosphere.
The answer is; B
During this time, the organism on earth began to evolve and live on land. Therefore these geologic events are marked by fossilized of dead primitive organisms such as archaebacteria within the early rocks
The initial report of the team formed by PURE may contain findings similar to the processes used in the disinfection of the water. Usual cases of ammonia presence in water are due to chloramine disinfection process. Also, they should also look into the storage of their facility and the end user which may also have a window of contamination.
