Arock contains 0.636 mg of 206pb for every 1.000 mg of 238u present. assuming that no lead was originally present, that all the 206pb formed over the years has remained in the rock, and that the number of nuclides in intermediate stages of decay between 238u and 206pb is negligible, calculate the age of the rock. (for 238u, t1/2 = 4.5 ✕ 109 years.)

Yes, endothermic means it turns cold. and some chemical changes include change of tempature.

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.

What is the gold assay