Usable chemical energy in food begins as energy

Which compound contains both ionic and covalent bonds? a) hbr b)cbr4 c)nabr d) naoh

How many grams of oxygen gas are contained in a 15 l sample at 1.02 atm and 28°c? show your work.

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.