Answer:what are the answer options?
Explanation
 
        
             
        
        
        
Answer:
proof in explanation
Explanation:
First, we will calculate the number of half-lives:

where,
n = no. of half-lives = ?
t = total time passed = 2100 million years
 = half-life = 700 million years
 = half-life = 700 million years
Therefore,

Now, we will calculate the number of uranium nuclei left ( ):
):

and the rest of the uranium nuclei will become thorium nuclei ( )
)

dividing both:

<u>Hence, it is proven that after 2100 million years there are seven times more thorium nuclei than uranium nuclei in the rock.</u>
 
        
             
        
        
        
The lithosphere because it includes the outer region of the earth including the crust and outer mantle
        
                    
             
        
        
        
Answer:
I SAVE D1K BY GIVING IT CPR
Explanation: