A rock sample has a half-life of 30 years, and it originally had 1,000g of radioactive material. After 90 years, how much of the original material is left?

What three factors shape our personality

This is a negative reaction to food that doesn’t involve the immune system

Answer for brilliant answer which of the following does best explains why cells remove waste? a. to create energy b. to form identical cells c. to break down glucose d. to maintain homeostasis