Two or more substances that have been combined but not chemically
changed make up

If 3 moles of a compound use 24 j of energy in a reaction, what is the a hreaction in j/mol?

6) (a) calculate the absorbance of the solution if its concentration is 0.0278 m and its molar extinction coefficient is 35.9 l/(mol cm). the depth of the cell is 5 mm. (b) what is the %t? (7) calculate the absorbance of the solution if the transmitted light intensity is 70% of the initial light beam intensity

Why is it that 85.48 rounded to two significant figures is 85 and not 86?