What is it?? plz help

As you watch a surfer ride a wave towards the shoreline, what is the shoreline? a) displacement reference b) reference point c) coordinate plane d) cartesian boundary

Calculate the mass of 0.750 mol of the following substance. na3po4. , i'm not quite sure on how to set up the problem to solve! : (

In order for a high temperature boiler or steam engine to produce superheated water, or steam: the heat source must be greater than 100°c the water must be permitted to evaporate quickly the system must be sealed and become pressurized above atmospheric pressure the vapor pressure must be kept below 760 mm(hg)