Which of the following chemical equations is balanced? a. h2 + cl2 4hcl b. 4h2 + 2o2 2h2o c. 4fe + 3o2 2fe2o3 d. 2fe + hcl fecl2 + h2

Which of the following elements does soil need in the largest quantities to sustain plant life? a. copper b. iron c. nitrogen d. zinc

1. environmental factors, such as ph and temperature, can affect the function of an enzyme. a. true b. false 2. which of the following is an organic molecules (ex. vitamins) that an enzyme? a. coenzyme b. product c. active site d. substrate 3. how do enzymes effect the speed of a chemical reaction? a. they speed it up b. they slow it down c. they have no effect on the speed of a reaction 4. during a chemical reaction, an enzyme is used up so that it can only be used one time. a. true b. false 5. which of the following results from a chemical reaction that is catalyzed by an enzymes? a. active site b. product c. substrate d. coenzyme

20 points and brainlist 1. london has suffered from terrible air pollution for at least seven centuries. why is the city so prone to its famous “london fog? ” what did london do to get rid of its air pollution? 2. why does air pollution cause problems in developing nations more than in developed ones?