What is the half-life of 99tc if a 500 g sample decays to 62.5 g in 639000 years

Theoretically, which metal should be the most reactive? hydrogen lithium francium fluorine

The diagram shows the structures of horse and cat forelimbs. what does the diagram suggest about the evolutionary relationship between these two mammals? a. they have homologous structures, indicating a common ancestor. b. they have analogous structures, indicating a common ancestor. c. they have homologous structures, indicating that they do not have a common ancestor. d. they have analogous structures, indicating that they do not have a common ancestor.

How do you lengthen a pattern piece? (family and consumer science, sewing)