The diagram below shows four columns that represent rocks from different geographic regions. Each layer within a column represents a brief period of time. Which of the four fossils would be the most useful as a reference to determine the age of newly discovered fossils? Why?

What? i don’t understand

Combustion is the act or process of burning. therefore, i believe the answer is  a: burning wood. 

Hello! mitosis and meiosis are the same, because they are both ways of dividing cells and reproducing cells. they are different in many ways, but the main one is that meiosis splits the number of chromosomes in 1/2, while the number of chromosomes remains the same for mitosis. plus, meiosis has two stage of division, unlike mitosis, where it has only one.

Caso4(s) < > ca+2 + so4^-2 ksp = [ca+2][so4^-2] = 2.4 x 10^-5 = [0.20][so4^-2] [so4^-2] =1.2 x 10^-4 ag2so4(s) ,> 2ag+ + so4^-2 ksp = [ag+]^2[so4^-2] = 1.5 x 10^-5 = (0.30)^2[so4^-2] [so4^-2] = 1.5 x 10^-5/0.09 = 1.7 x 10^-4 caso4 would precipitate first since it requires less so4^- to form a saturated solution.  i believe this is right, i hope it !