Answer:
Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
Please give brainliest
 
        
             
        
        
        
Answer:
no-one God is the highest
Step-by-step explanation:
 
        
                    
             
        
        
        
40,000,000 + 20,000 + 3,000 + 30 + 2
and 
forty million twenty-three thousand thirty-two 
 
        
             
        
        
        
Answer:
V ≈ 527.79
Step-by-step explanation:
Formula is V= πr2h 
therefore
V = π * 4 * 2 * 10.5
V = π * 8 * 10.5
V ≈ 527.79