If the radioactive isotope of a particular element has a half-life of 15,000 years, how old is a sample that has 12.5% of the parent isotope remaining

What provides structure to the human body?

Ahypothrticalax type of ceramic material is known to have a density of 2.10 g/cm3 and a unit cell of cubic symmetry with a cell edge length of 0.57 nm. the atomic weights of the a and x elements are 28.5and 30.0 g/mol, respectively. on the basis of this information, which of the following crystal structures is (are) possible for this material: sodium chloride, cesium chloride, or zinc blende

What is the mass defect of a mole of nuclei with 1.8 x 10^15 j/mol binding energy?