Which of the following is a radioisotope used to date rock formations older than 50,000 years?
a. carbon-14.
b. uranium-235.
c. cobalt-69.
d. carbon-12.

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

This is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table.

Each pair of clay balls represents to planetesimals if each plane test molluscum pound of the same material and is separated by the same distance which pair experiences the greatest gravitational attraction