Carbon-14 is a radioactive isotope. It is found in the air in carbon dioxide molecules. The amount of carbon-14 in the air has stayed the same for thousands of years. There is a small amount of radioactive carbon-14 in all living organisms because it enters the food chain. Once an organism dies, it stops taking in carbon-14. The carbon-14 it contained at the time of death decays over a long period of time, and the radioactivity of the material decreases. The approximate time since the organism died can be worked out by measuring the amount of carbon-14 left in its remains compared to the amount in living organisms. In 1991, two hikers discovered a mummified man, preserved for centuries in the ice on an alpine mountain. Later called Ötzi the Iceman, small samples from his body were carbon dated by scientists and found to contain approximately 47% less carbon-14 than the amount found in living organisms. Based on this finding, how old are the remains of Ötzi the Iceman estimated to be?

Many reactions take place in aqueous solution. when potential reactants are mixed, a reaction will occur if there is some driving force that favors the formation of products. it is often convenient to categorize reactions in terms of these driving forces: precipitate formation, in which an insoluble solid is formed, weak electrolyte formation, as in a neutralization reaction involving water, or transfer of electrons, as in a redox reaction. these reactions can be represented by full molecular equations, which contain all species in the reaction mixture, or by net ionic equations, which show only the species that actually undergo a change. the latter does not contain the spectator ions, which do not undergo a net change or do not take part in the reaction. part a when the following two solutions are mixed: k2co3(aq)+fe(no3)3(aq) the mixture contains the ions listed below. sort these species into spectator ions and ions that react. drag the appropriate items to their respective bins. view available hint(s) spectator ions ions that react part b what is the correct net ionic equation, including all coefficients, charges, and phases, for the following set of reactants? assume that the contribution of protons from h2so4 is near 100 %.ba(oh)2(aq)+h2so4(aq)→ express your answer as a chemical equation. view available hint(s) nothing provide feedback

Calculate the frequency of a wave in a spring toy. the wave has a speed of 1.1 meters per second and a wavelength of 0.1 meters. *

Calculate the energy required to ionize a hydrogen atom to an excited state where the electron is initially in the n = 5 energy level. report your answer in kilojoules