When magnesium burns in cl2 , it forms magnesium chloride. which element is reduced?

Scientist wants to react a barium chloride salt with an acid. to speed up the reaction, the scientist crushes the barium chloride salt until it is a fine powder. this speeds up the reaction by a. increasing the ph of the salt. b. increasing the surface area of the salt. c. increasing the pressure of the salt. d. increasing the temperature of the salt. im thinking more a not 100% sure

Given sno2 + 2h2 - sn + 2h20 tin oxide reacts with hydrogen to produce tin and water. how many moles of sno2 are needed to produce 500.0 grams of sn?

How many mmols of tris-hcl are there in 100 ml of a 100 mm tris-hcl buffer solution at ph 8.1? note that the 100 mm refers to the sum of tris and tris-hcl concentrations?