Azero-order reaction has a constant rate of 4.40×10−4 m/s. if after 45.0 seconds the concentration has dropped to 1.50×10−2 m, what was the initial concentration? express your answer with the appropriate units.

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

The is a particle with one unit of positive charge a. proton b. positron c. electron d. nucleus awnser quick it is a important science test!

Which of these would be caused by a chemical change? a) the formation of lava. b) sedimantary rock layering over time. c) metamorphic rock forming from igneous. d) metamorphic rock eroding to form sedimentary rock.