Mass doesn't change, no matter where you take it.
Your first impression of ' 0 ' is totally correct.
Imagine you are in a swimming pool 30m deep. Assuming you know that water is denser than air, you would know that the 30m of water above you will carry more weight, and press down on your body. Say you were in a swimming pool 60m deep, you would be sandwiched between 30m of water pressing down on you, and the upthrust created by the 30m of water below you.
In a building 30m up, the pressure will be regulated, as you are in a building. The floor will be strong enough to support the weight of the body, and the body will not recoil into itself.
The sound wave never actually loses energy, the bulk of energy it had at the beginning of the sound, is spread out into a sphere, making it decrease in amplitude and frequency.
Answer:
2Mg + O2 = Reactant | 2MgO = Product
Explanation:
It is pretty simple, look:
The elements that are being added (or in the majority of the cases, the one who are in the left side) are always the Reactant.
The other side is the product of the reactants.
It is like a mathematic formula
We some the numbers to get the result, the numbers are the reactants and the result is the product.
(I hope you didn´t get confused)