What is the cooling and hardening of magma or lava?

Why don't all places on earth receive the same amount of direct sunlight at the same place?

Which statements are accurate about snow flakes

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