Answer:
0.159 M
Explanation:
convert from mL to L then use the equation:
M1V1 = M2V2
rearrange to find M2


Complete Question
Questions Diagram is attached below
Answer:
* 
* 
* 
Explanation:
From the question we are told that:
Temperature 
Pressure 
Volume
Generally the equation for gas Constant is mathematically given by



Therefore
Work-done



Generally the equation for internal energy is mathematically given by


Therefore



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