Cerium-143 is a radioactive isotope that decays to produce praseodymium-143. The half-life for cerium-143 is approximately 33 hours. If 12.5 g cerium-143 remains from a 100-g sample, which statement is true? Select all that apply. A.
Cerium-143 decayed for 132 hours.

B.
Cerium-143 decayed for 99 hours.

C.
Four half-lives have passed.

D.
Three half-lives have passed.

E.
Cerium-143 decayed for 166 hours.

F.
Two half-lives have passed.

Discuss how the hardness or softness of the landing surface is related to the time required to stop the egg

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.