Quantitative observations always include a. numbers b. words c. time d. symbols

Use the standard enthalpies of formation for the reactants and products to solve for the δhrxn for the following reaction. (the δhf of c2h4 is 52.26 kj/mol, co2 is -393.509 kj/mol, and h2o is -241.818 kj.) c2h4 (g) + 3o2(g) 2co2 (g) + 2h2o(g) δhrxn = the reaction is .

Astudent is trying to create a table that compares hypotheses, theories, and laws. hypothesis theory law do scientific researchers formulate it? yes yes yes does it explain why things happen? yes yes no yes yes yes is it used to make predictions? no yes yes which of the following questions would most likely fill the blank in the table? is it an intelligent guess? is it newly formulated? is it based on observations? has it been proved?

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.