Question

23) In the formula A(O)- Agekt, A is the amount of radioactive material remaining from an initial am a given time t, and k is to e decays at a rate of 0.3% annually. Determine hehalf ife of this isotope, to the nearest year is a negative constant determined by the nature of the material. A certain radioactive A) 231 yr B) 100 yr C) 167 y D) 2yr 24) The half-life of an element is 5.0 x і012 yr. How long does it take a sample or the element to deay to or its original mass? Use A(O)- Agekt where Ao is the initial amount, k is a negative constant determined by the nature of the material, and t is the time. (Express results in scientific notation, rounded to the nearest hundredth.) A) 1.77 1012 yr B) 3.68 x 1012 yr )456 1012 yr D) 9.12 1011 yr 25) An artifact is discovered at a certain site. If it has 72% of the carbon-14 it originally contained what is the approximate age of the artifact to the nearest year? A) 1141 yr B) 5760 yr C) 2628 yr D) 2240 yr

Answer 1