What oxide is produced by the sparking of air in car engines? (option question)
iron oxide,
copper oxide,
potassium oxide,
calcium oxide,
lead oxide,
nitrogen dioxide.

Long term exposure to waves can cause sunburns and skin cancer. a) visible b) infrared c) gamma rays d) ultraviole

Mike and mitchell decide to have a foot race. they mark off a stretch of 100 yards, and recruit cindy to work the stopwatch. after running the race and looking at the results, cindy declared that mitchell was the fastest. so how did the boys times compare?

How many protons, electrons, and neutrons are in each of the following isotopes? a. zirconium-90 b. palladium-108 c. bromine-81 d. antimony-123