1. ¿Por qué los cuatro elementos (tierra, fuego, viento y aíre) fueron esenciales para la historia de la Tabla Periódica y de la Química? 2. ¿Qué aportes ha dado la Tabla Periódica a la Ciencia y la Tecnología? Escribe 2 ejemplos. 3. ¿Qué beneficios le ha traído a la familia el descubrimiento de la tabla periódica? 4. ¿Qué otro nombre recibe cada grupo de la tabla periódica?

1. variations in a population of moths allow for some of its members to be able to adapt to environmental changes. the better adapted of the moths will be able to survive the change and thus prevail as the “fittest” of the species. (a) describe three mechanisms in which variation can occur within a species population. (b) explain which mechanism or mechanisms would be responsible for the survival of a population of peppered moths better than white moths in an environment affected by industrial soot. justify your answer.

Radiometric dating is used to tell the absolute age of materials by studying the decay rate of radioactive isotopes. the decay rates of isotopes are constant and are expressed as .

19. a cell is viewed under a microscope and is found to have two nuclear envelopes and spindles that appear to be breaking apart. which phase of mitosis is the cell most likely in? a. metaphase b. prophase c. telophase d. anaphase