A half life of 29 years means that after 29 years, only half of this isotope would be left due to radioactive decay. If we start of with 2000g of it and leave it for 116 years, it would undergo 4 "half=lives". 116/29 = 4. So after the first half life, we would have 2000g/2 = 1000g left. After the second, we would have 500g left, after the third, 250g so after 4 half lives or 116 years, there would be 125 g of Strontium-90 left at the site.
Energy is absorbed bc endo means in so endothermic means energy is absorbed
Answer: 
Explanation:
Given
Mass of iron piece is 
Heat absorbed 
Temperature changes from
i.e.

Heat absorbed is given by ![Q=mc\Delta T\quad [c=\text{specific heat of material}]](https://tex.z-dn.net/?f=Q%3Dmc%5CDelta%20T%5Cquad%20%5Bc%3D%5Ctext%7Bspecific%20heat%20of%20material%7D%5D)
Insert the values

Thus, the specific heat of iron is 
Answer:
1
Explanation:
there is only one sulphur (S) atoms in the formula for sodium sulphate
Answer:
0.5474
Explanation:
3.22 x 0.17
\/
322 x 17 = 5,474
[] There are four places "after" the decimal in 3.22 and 0.17 combined, meaning we move the decimal to the right four times in our current answer
-> 5,474 becomes 0.5474
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather