Which one of the following is not a valid expression for the rate of the reaction below? 4nh3 + 7o2 → 4no2 + 6h2o.

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

Which early modernism trend in art focused on prehistoric or exotic cultures? a. primitivism b. expressionism c. impressionism d. total serialism

Analyze the forces acting on a cyclist who is slowing down as he or she climbs a hill