Answer:
I think it is: Some of the energy is converted into thermal energy.
Explanation:
Please let me know if I am wrong so I can fix it :)
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
Explanation:
It is given that volume is 0.50 L and molarity is 0.485 M. Hence, number of millimoles will be calculated as follows.
Number of millimoles = Molarity × Volume
As there are 1000 mL in 1 L. So, 0.50 L equals 500 mL.
Therefore, putting the given values into the above formula as follows.
Number of millimoles = Molarity × Volume
= 0.485 M × 500 mL
= 242.5
Thus, we can conclude that 242.5 millimoles of copper(II) sulfate has been added by the chemist to the flask.
The atomic radius decreases
