2H++ Na2CO3 -> 2Na++ H2O + CO2

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The air exhaled from the lungs of a smoker has a concentration of 24 ppm co. express the concentration as a percent.

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.