How is the half-life of a radioactive material useful for radioactive dating?

Calculate the atomic mass of element X if there are two isotopes of this element (X-24 and X-28) and 75% of all X atoms are X-28 isotopes. 52 amu 4 amu 27 amu 26 amu

A 5-column table with 2 rows. Column 1 is labeled number of protons, with entries A and D; column 2 is number of neutrons, with entries 7 and E; Column 3 is atomic number, with entries B and 26;

What are the three main groups in the periodic table

When three pairs of electrons are shared in a molecule, what shape will the molecule be? a. tetrahedral b. trigonal planar c. bent d. linear

Which is the correct net ionic equation for the following reaction: 2HI (aq) + Ca (OH) 2 (aq) Imported Asset CaI2 (aq) + H2O (l) ? A. H + (aq) + Ca+2 (aq) + 2 I - (aq) Imported Asset CaI2 (aq) B.

2 human activities that contribute to runoff into water systems

Which of the following is an example of geographic isolation? A. a population of salmon dies out because they cannot find food. B. a zebra with a long mane moves into a population of zebras with short manes. C.

What are moles in chemistry?

How did John dalton describe atoms?

Which of the following statements describes a physical property? The substance has a higher density than water. A. The substance forms a solid when reacted with silver nitrate. B. The substance is highly reactive. C.