Determine la cantidad de masa en moles de H3PO4 necesaria para preparar 250 ml de una solución acuosa (con H2O) 0,015M.

0.2348 grams of pbcl2 used to form 44.0 ml of solution.

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.