Tryptophan is the precursor to the synthesis of brain serotonin. The pH of the brain is buffered at 7.2. What substance(s) would you use to make a buffer with a pH close to that of the brain

here is the answer

water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. weathering is the breaking down or dissolving of rocks and minerals on earths surface. once a rock has been broken down, a process called erosion transports the bits of rock and minerals away.