A. The hydrogen molecule has a structural formal that looks like this: H—H. The oxygen molecule has a structural formula that looks like this: O=O (except you should make the lines longer). When you combine the molecules, it has a structural formula that looks like this:
O
/ \
H H
b. O=C=O (again, make the lines a little longer)
c. space-filling model of hydrogen looks like this oo (circles should be touching) and the space-filling model of carbon dioxide should look like this OoO (circles should be touching)
Chemical reactions release or absorb heat or other energy or may produce a gas, odor, color change, or sound. If you don’t see any of these indications, a physical change likely occurred. Be aware a physical change may produce a dramatic change in the appearance of a substance. This doesn’t mean a chemical change occurred. Examples of a chemical change would be rusting iron, or burning wood, or even cooking. Examples of physical changes would be tearing paper, boiling water, or freezing popsicles.
Answer: 4
Explanation: Your counting 4 for each interval. 9+4 =13 13+4 =17 17+4 =21 and so on.