Carbon-14 is a radioactive substance produced in the Earth's atmosphere and then absorbed by plants and animals on the surface of the earth. It has a half-life (the time it takes for half the amount of a sample to decay) of approximately 5730 years. Using this known piece of information, scientists can date objects such as the Dead Sea Scrolls. The function N = N₀e^-trepresents the exponential decay of a radioactive substance. N is the amount remaining after time t in years, N₀is the initial amount of the substance and is the decay constant.

1. Find the rate of change of an initial amount of 1 gm of carbon-14 found in the scrolls, if the decay constant is given as = 1.21 x 10-4.
2. If the percentage of carbon-14 atoms remaining in a sample is 79%, how old is the sample?