Calcium-45 has a half-life of 162.7 days. if four half-lives have elapsed, how much time has passed?

650.8 days

Explanation:

if the half-life is 162.7 days and the number of half-life days has elapsed 4 times.

To know the number of days that have passed we must multiply the half-life by 4

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be