12. which of the following statements is true about a nickel-cadmium dry cell? (points : 3) the cathode reaction is cd + 2oh cd(oh)2 + 2e. the cathode reaction is cd + nio2 + 2h2o cd(oh)2 + ni(oh)2. the cathode reaction is nio2+ h2o + 2e ni(oh)2 + 2oh. the anode reaction is nio2 + h2o + 2e ni(oh)2 + 2oh.

For which one of the following reactions is the value of δh° rxn equal to δh° f for the product? a. 2 h2 (g) + o2 (g) → 2 h2o (l) b. n2 (g) + o2 (g) → 2 no (g) c. 2 h2 (g) + o2 (g) → 2 h2o (g) d. h2o (l) + 1/2 o2 (g) → h2o2 (l) e. none of the above

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas. in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?