Which balanced equation represents a chemical change? a. h2o(l) → h2o(s) + energy b. 2 h2o(l) + energy → 2 h2(g) + o2(g) c. h2o(g) → h2o(l) + energy d. h2o(l) + energy → h2o(g)

Okay, so what you first do with this  type of question is think about what a chemical change is. A chemical change is a change that can not be reversed. A physical change is something that can be reversed or done using temperature. e.x. Water freezing into ice is a physical change, where as combining vinegar and baking soda together releases a gas, which is chemical, or iron rusting in the presence of oxygen.  Which one of these equations has one chemical molecule set that produces a different set?

fe 55.85 g/mol and h2o 18.02 g/mol.

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )