Determine how long will it take for the atoms

Question

1.Determine how long will it take for 6.00 x 10²⁰ atoms of Zn-71 to decay to leave only 6.00 x 10¹⁰ atoms?

2. Given that the mass of 1 mole of deuterium is 2.01410 g, and the mass of one mole of helium is4.00260 g, determine the number of moles of deuterium required to heat the swimming pool from 12.00 degrees C to 25.00 degrees C. The fusion of two deuterium atoms are used to heat cylindrical swimming pool the measures 5.00 x 10^-6 Mm (mega meters) in diameter by 2.00 x 10^-9 Gm(Gig meters) in depth.