What is the process in the moon, that created the Maria, highlands ,and rilles

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

In what way does renewable energy differ form nonrenewable energy?

Which of the following graphs represents exponential decay