A chemical compound decays at a rate of 5% per year. If the initial size of the compound is 100 grams, what is the exponential function that represents the rate of decay?

The exponential function that represents the rate of decay can be represented by the formula:

y = 100 * (0.95)^x

Where:
y = size of compound after x years
x = number of years

So, the exponential function that represents the rate of decay is:

y = 100 * (0.95)^x