Need what describes using organisms that were only alive during a specific time period to estimate the unknown age of items? radioactive dating law of superposition relative dating index fossils

What is driving behind plate tectonics (plate movment)? a) gravity only b) inertia c) convection and gravity d) the sun theres no option for science so i picked chemistry. plz

Several kinds of bears are found on earth. most bears are brown or black, but one type of bear, the polar bear, is white. what process led to this difference in fur color? explain your answer.

Consider the reaction: n2(g) + o2(g) ? 2no(g) kc = 0.10 at 2000oc starting with initial concentrations of 0.040 mol/l of n2 and 0.040 mol/l of o2, calculate the equilibrium concentration of no in mol/l how would this be done?