The mass of cesium left afer 120 years if the original mass of cesium is 8640 with an half-life of 30 years, is 540 grams.
<h3>What is half-life?</h3>
This can be defined as the time taken for half the amount of a radioactive substance to decay.
To calculate the amount of cesium left after 120 years, we use the formua below.
Formula:
- R' = R/(
)............. Equation 1
Where:
- R = Original amount of Cesium
- R' = New amount of cesium
- T = Total time
- t = Half-life
From the question,
Given:
- R = 8640
- T = 120 years
- t = 30 years
Substitute these values into equation 1
- R' = 8640/(
) - R' = 8640/

- R' = 8640/16
- R' = 540 grams.
Hence, The mass of cesium left afer 120 years is 540 grams.
Learn more about half-life here: brainly.com/question/25750315
B!
The equation x-4y= -4 is the graph, right? So that means when x is, lets say, 2, then:
2-4y= -4
Simplify
-4y=-6
y=3/2
Now if you think about it, if you plug in any number for x and get some value of y, that is the point on the graph at that x value.
Hope this helps!
Answer D.
Insert (2, 2) in for x and y in the equations.
2(2)+ 3(2) = ?
? = 10
4(2) + 5(2) = ?
? = 18