According to what is known about chemical equilibrium and Le Chatelier's principle, when you increase the amount of the reactants, the reaction will be moved to the products, this is because, the most reactants we have the most products we can produce.
From the given choices, the one that goes according to this reason is the third one: The volume of water vapor increases.
 
        
             
        
        
        
Answer:
No question so I'm just taking the points
 
        
             
        
        
        
Answer:
30, 50
Explanation:
Hello,
In this since an element's atomic number is equal to the number of protons in its atom, we can infer that selenium's atomic number is 30. Moreover, due to the fact the the neutrons are equal to the atomic mass minus the atomic number or the number of protons, by knowing the number of neutrons we compute the atomic as follows:

Thus, answer is 30, 50.
Best regards.
 
        
             
        
        
        
.774atm
First, look at what you have and look at the equations you can use to solve this problem. The best equation would be PV=nRT. 
P being pressure, V being volume, n being moles, R being the gas constant, and T being temperature.
Before you start doing any of the math, make sure of two things. Since you're looking for pressure, you'll need a gas constant. When I did the problem, I used the gas constant of atm or atmospheres which is .0821. 
Also! Remember to always convert celsius into kelvin, to do this, add 273 to the given celsius degree. After this is all set and done, your equation should look like this:
P = 
The reason that the equation is divided by the volume is due to the fact that you need to isolate the variable or pressure.
Multiply everything on the top and divide by the bottom and you should receive the final answer of .774atm.
Hope this helps!
 
        
             
        
        
        
Weighs 0.001836 gram per cubic centimeter or 1.836 kilogram per cubic meter
Try to see if this helps