The Radiochemist, Will I

Multiple Choice

The radiochemist, Will I. Glow, studied thorium-232 and found that 2.82 × 10^-7 moles emitted 8.42 × 10⁶ α particles in one year. What is the decay constant for thorium-232?

A) 3.35 × 10-¹⁴ yr^-1
B) 4.96 × 10-¹¹ yr^-1
C) 1.40 × 10¹⁰ yr^-1
D) 2.99 × 10¹³ yr^-1
E) None of these choices are correct.