A propane stove burned 470 grams propane and produced 625 grams of water (this is the actual yield) C3H8 +5O2=3CO2+4H20. What was the percent yield of water for the stove?

I would really appreciate the help. I don't understand how to begin.

Asap , 8th grade science 50 points 1) a 2kg bowling ball sits on top of a building that is 40 m tall. what type of energy does it have? potential energy energy of acceleration kinetic energy chemical energy 2) a 2 kg bowling ball sits on top of a building that is 40 meters tall. how much potential energy does it have? 784 j 80 j 784 n 78.4 j 3) a 4 kg bowling ball rolls at a speed of 5 m/s on the roof of a building that is 30 meters tall. what type of energy does the bowling ball have? both potential and kinetic energy kinetic energy potential energy speed 4) a 4 kg bowling ball rolls at a speed of 5 m/s on the roof of a building that is 30 meters tall. what is its kinetic energy? 50 j 10 j 120 j 1,176 j 5) an 8 kg bowling ball rolls at a speed of 10 m/s on the ground. what type of energy does the bowling ball have? kinetic acceleration potential speed 6) an 8 kg bowling ball rolls at a speed of 10 m/s on the ground. what is its kinetic energy? 40 j 80 j 160 j 400 j 7) a 20 kg child is tossed in the air by her parent. what is her kinetic energy when she is 2 meters off the ground traveling at 5 m/s? 200 j 40 j 100 j 250 j 8) a 1,000 kg car has 50,000 j of kinetic energy. what is its speed? 100 m/s 150 m/s 50 m/s 10 m/s 9) a 200 kg boulder has 39,200 j of gravitational potential energy. what height is it at? 50 m 20 m 150 m 200 m 10) a 1 kg model airplane has 12.5 j of kinetic energy and 98 j of gravitational potential energy. what is its speed? 5 m/s 10 m/s 15 m/s 20 m/s

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

Chemistry worksheet - i am not sure what they are asking for exactly?