What element is mostly used in magnets, gold or cobalt?

What is a metal replacement reaction

1. if you have a gas at 127 degrees c, what is it's absolute temperature (kelvin)? a. 200kb. 300kc. 400kd. 500k2. if you had a gas whose absolute temperature measured 45 k, what is that temperature in celsius? a. -228 cb. -300 cc. 125 cd. 112 c

What are fossils of organisms that existed over a wide area but only for a limited time period called?