1) This is a definition.
2) Protons are given by the bottom number (since atomic number = number of protons).
3) Neutrons = (mass number)-(atomic number), which are the top and bottom numbers, respectively.
4) Nuclear fusion involves combining two things together, which is only reflected by the last option.
5) This is a fact.
6) This is a fact.
7) This is a fact.
8) This is a fact.
9) The correct option is the explanation.
Answer:

Explanation:
Hello
In this case, given the reaction:

It means that since the coefficients preceding phosphorous and phosphorous trifluoride are 1 and 4, the correct mole ratio should be:

Because given the mass of phosphorous it is convenient to convert it to moles and then cancel it out with the moles on bottom of the mole ratio.
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Answer:
403 mL
Explanation:
First, I will assume that the mole is 1, because you are not specifing this.
Now, with the innitial data, we need to get the pressure:
T = 65+273 = 338 K
V = 500 / 1000 = 0.5 L
Now if:
PV = nRT
Then:
P = nRT/V and V = nRT/P
Let's calculate the P:
P = 1 * 0.082 * 338 / 0.5 = 55.432 atm
The standard temperature is 0° C or 273 K so, the volume is:
V = 1 * 0.082 * 273 / 55.432
V = 0.40384 L or simply 403.84 mL
<span>Molar mass is the mass in grams of one mole of any pure substance.</span>
Yes, the chemical reaction occurs because new substance is formed and heat energy is released.
<h3>
What is chemical reaction?</h3>
Chemical reaction is a process in which one or more substances i.e. the reactants, are converted to one or more different substances i.e. the products so we can conclude that the chemical reaction occurs because new substance is formed and heat energy is released.
Learn more about chemical reaction here: brainly.com/question/11231920