[ 567 ] Physical Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Hydrogen peroxide (H 2 O 2 ) is stored in dark, opaque containers to slow the natural breakdown of the compound. The reaction is summarized by this formula: 2 H 2 O 2 → _____ H 2 O + O 2 Write the missing number of water molecules on the line. In a chemical formula, subscripts show the ratio of one kind of atom to another. For example, NH 3 shows that there are three hydrogen atoms for every one nitrogen atom. Examine the following ratios: • twice as many sodium atoms as carbon atoms • three times as many oxygen atoms as carbon atoms Which chemical formula correctly shows the ratios described? A. Na 2 CO 3 B. NaCO 3 C. Na 3 CO 2 D. Na 6 CO 12 What is velocity?