Answer:
6
Explanation:
The atomic number for phosphorous is 15, meaning that it has 15 electrons (and protons). The first and second shells would be filled up with 2 and 8 electrons respectively, leaving 5 which goes on the third shell, which is also the valence shell, meaning phosphorous has 5 valence electrons.
Since the atomic number of sulfur is 16, the first and second shells are also filled up with 2 and 8 electrons respectively, leaving 6 to be on the third shell, the valence shell. Hence, sulfur has 6 valence electrons.
This question is asking for a method for the determination of the freezing point in a solution that does not have a noticeable transition in the cooling curve, which is basically based on a linear fit method.
The first step, would be to understand that when the transition is well-defined as the one on the attached file, we can just identify the temperature by just reading the value on the graph, at the time the slope has a pronounced change. For instance, on the attached, the transition occurs after about 43 seconds and the freezing point will be about 4 °C.
However, when we cannot identify a pronounced change in the slope, it will be necessary to use a linear fit method (such as minimum squares) to figure out the equation for each segmented line having a significantly different slope and then equal them so that we can numerically solve for the intercept.
As an example, imagine two of the segmented lines have the following equations after applying the linear fit method:

First of all, we equal them to find the x-value, in this case the time at which the freezing point takes place:

Next, we plug it in in any of the trendlines to obtain the freezing point as the y-value:

This means the freezing point takes place after 7.72 second of cooling and is about 1.84 °C. Now you can replicate it for any not well-defined cooling curve.
Learn more:
Answer:
Krypton does not react with anything, but it reacts with fluorine gas
Explanation:
Salutations!
<span>In a laboratory experiment, John uses a mesh to separate soil particles from water. Which technique of separation is he using?
The technique that John is using is the filtration technique. Filtration is a technique to separate the solid which is insoluble from the liquid. For instance: Sand and water, sand is insoluble, thus it stays in the filter paper, while the water proceeds through the filter paper.
Hope I helped :D</span>
<u>Answer:</u>
<u>For Part A:</u> The partial pressure of Helium is 218 mmHg.
<u>For Part B:</u> The mass of helium gas is 0.504 g.
<u>Explanation:</u>
We are given:

To calculate the partial pressure of helium, we use the formula:

Putting values in above equation, we get:

Hence, the partial pressure of Helium is 218 mmHg.
To calculate the mass of helium gas, we use the equation given by ideal gas:
PV = nRT
or,

where,
P = Pressure of helium gas = 218 mmHg
V = Volume of the helium gas = 10.2 L
m = Mass of helium gas = ? g
M = Molar mass of helium gas = 4 g/mol
R = Gas constant = 
T = Temperature of helium gas = 283 K
Putting values in above equation, we get:

Hence, the mass of helium gas is 0.504 g.