Carbon-11 is one of the radioactive isotopes of carbon with half-life period of 20 minutes. What fraction of the initial number of c-11 atoms in a sample will have decayed away after 80 minutes ?.

Two technicians are discussing how to test a car's exhaust by holding a small piece of paper within an inch of the tailpipe mouth. technician a says that if the paper is vibrating due to a "puffing" output from the tailpipe, this signals a smoothly running engine. technician b says that if the paper is being drawn toward the tailpipe, this could indicate burned exhaust valves. who is correct? a. technician b b. both technicians a and b c. technician a d. neither technicians a or b

You are getting ready to transport troops in a m1152 configured with cargo cover and troop seats which of the following should you do before starting out

In a cooking context,which of the following materials is the best heat conducter?