What is the oxidation state of lead

Which of the following describes the entropy change as a solution is made from a liquid and solid

Reacting masses1 calcium carbonate breaks down on heating to produce calcium oxide and carbondioxide gas. caco3 + cao + co2a student heats 15 g of calcium carbonate strongly in a crucible. relative atomic masses (a): ca = 40, c = 12, o = 16.calculate the mass of calcium oxide produced by this reaction.(5 marks)

Jenny places a strip of ph paper into a solution. when she removes the ph paper, it has turned yellow-green. what should jenny do next to determine the ph of her solution? a. use a different testing method because the ph paper should not change colors b. place the ph paper into a machine that reads the ph of the solution c. compare the ph paper's color with the color of ph paper from another solution d. compare the ph paper's color with a chart of colors and ph ranges