The substance of 256 gm will be decayed into 1 gm in 800 years.
Step-by-step explanation:
Given,
The substance decays 75% in every 600 years.
Amount of substance = 256 gm
To find the the time the substance to decay to 1 gm.
Now,
75% decay in 600 years
1% decays in 600÷75 years
100% decays in ×100 years
= 800 years
Hence,
The substance of 256 gm will be decayed into 1 gm in 800 years.