Answer:
From the periodic table, Atomic number of fluorine is 7 and atomic mass is 19
Answer:
By absorbing energy on evaporation and releasing it on condensation, it keeps water cool when the air is hot and warm when the air is cool.
Answer:

Explanation:
Hello there!
In this case, according to the given information, it will be possible for us to use the Dalton's law, in order to solve this problem. However, we first need to calculate the mole fraction of oxygen by firstly calculating the moles of each gas:

Next, we calculate such mole fraction as follows:

Then, given the following equation:

So we solve for the total pressure as follows:

Regards!
The answer to this problem is
P - phosphorus