Are you asking what that says in english ?
Answer:
B
Explanation:
You might want to pick "A sound is created" No that answer is just fine. If you listen when sitting around a campfire, you might hear the crackling of what is burning. Burning is an excellent example of a chemical change. Wood becomes ash.
The answer is a change in the state of matter. (B). That need not indicate a chemical change. In fact, most of the time, a change in matter is a physical change.
Answer: B
a micron is a millionth of a metre
So in this equation, 3 oxygen will react with 1 ethylene.
then, you convert from 12.9 Liters to moles.
1 mole = 22.4 Liters of gas.
x moles = 12.9 liters
So, 22.4x = 12.9, which means that x = 12.9/22.4, and you get about 0.6, then you divide by 3 because you have 3 Oxygen, and you get about 0.2.
So, 0.2 moles of ethylene C2H4 can react with 12.9 liters of Oxygen Gas.
Hope this Helps :)