A) How long will it take for 40.0 grams of Radium-226 (Ra-226) to decay to leave a total of 2.5 grams of Ra-226? Ra-226 has a half-life of 1600 years. B) If there are 80.0 grams of Neptunium-240 (Np-240), how much Neptunium-240 will remain after 4 hours? The half-life of Neptunium-24 is 1 hour.

a) 6400 years

b) 5 grams

Explanation:

a) to get 6400 years, the 40 grams is halved 4 times to get to 2.5g and 4 times 1600 is 6400

b) 80 is halved 4 times and the final result you get is 5 grams

80/2= 40/2= 20/2=10/2=5

each divided by 2 represents 1 hour

it's not c. i took the quiz and got it wrong. so my best guess is b.

have a great day, and hope this .

emerging idea only occurs as a raw idea that could appear out of nowhere. meanwhile, to reach scientific consensus , that idea must be structured and tested over and over again through various experiments. the scientific consensus transforms the raw idea into idea that is more reliable through the process of scientific elimination.