Answer:
correct option is b. 31.3 m/s
Explanation:
given data
artificial gravity a1 = 1 g
artificial gravity a2 = 2 g
diameter = 100 m
radius r= 50 m
speed v1 = 22.1 m/s
solution
As acceleration is ∝ v²
so we can say
.....................1
put here value
solve it
v2 =
× 22.1
v2 = 31.25 m/s
so correct option is b. 31.3 m/s
Via half-life equation we have:

Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes. By plugging those values in we get:

There is 6.25 grams left of Ra-229 after 12 minutes.
In terms of the scientific method, the immediate purpose of doing an experiment is gathering data. You cannot draw conclusions or form a proper hypothesis without some sort of basis and data.