Answer:
0.75 grams
Explanation:
Today we have 6 grams
In 30 years, 3 grams remain
In 60 years 1.5 grams remain
in 90 years 0.75 grams remain
mathematically It would look like this
m = 6(0.5⁽ⁿ/³⁰⁾) where n is number of years
I already said it but its reactivity
Sound waves or bounces off the wall and light waves are waves of light