Which of the following are examples of exponential decay? Select al that apply?

1- A vehicle depreciates 13% each year.
2- A tree is doubling in height each year. an investment earns a 5% interest each year.
3- An investment earns a 5% interest each year.
4- Air pressure decreases 12% for every 1000 meters in height.4
5- The population of a town is growing at an annual rate of 3.5%
6- A retirement account decreases by $12,000 each year.
7- A radioactive element has a decay rate of 10%