Which of the following lists the earth’s layers in order from hottest to coldest in temperature?
a. outer core, mantle, inner core, crust
b. crust, mantle, outer core, inner core
c. inner core, outer core, mantle, crust
d. mantle, crust, inner core, outer core

The first-order reaction a→2b+c has rate constant 0.538 s−1. if the initial concentration of a is 0.867 mol l−1, what is the half-life of the reaction in seconds? remember to use correct significant figures in your answer (round your answer to the nearest hundredth). do not include units in your response.