Answer:
6.70 grams of krypton-81 was present when the ice first formed
Explanation:
Let use the below formula to find the amount of sample

where

here
t = 458,000 years
= 229,000
= \
n =
= 2.000
Now substituting the values




In evaporation due to internal heat, kinetic energy of molecules increases and they come to the top and take out that heat with them when they evaporate thus causes cooling
in boiling as heat is given to the molecules so their kinetic energy increases and they start vibrating with great energy and thus causes heating