Answer:
Thorium 227 (also known as Radioactinium)
I'm pretty sure the moon would be a crescent within the 10 day period because it takes about 28 days for the moon to go through the different stages.
When you look at this, you might not be sure which way to divide ...
Should you divide 6 by 5 or 5 by 6 ?
Here's a case where you can use your units to decide.
The question wants to know the 'period'. That's a length of time,
so the answer needs to have units of time.
If you divide 'cycles' be 'time', you'll get 'cycles/second'.
That's Hz. It's frequency, not time.
If you divide 'time' by 'cycles', you'll get 'seconds/cycle'.
That's time, and it's exactly the definition of 'period'.
Period = (6 seconds) / (5 cycles)
= (6 / 5) seconds/cycle
= 1.2 seconds
I believe the answer is d
