Given which are missing in your question:
the flask is filled with 1.45 g of argon at 25 C°
So according to this formula (Partial pressure):
PV= nRT
first, we need n, and we can get by substitution by:
n = 1.45/mass weight of argon
= 1.45 / 39.948 = 0.0363 mol of Ar
we have R constant = 0.0821
and T in kelvin = 25 + 273 = 298
and V = 1 L
∴ P * 1 = 0.0363* 0.0821 * 298 = 0.888 atm
Equation for the standard formation of solid sodium orthosilicate:
4 Na(s) + Si(s) + 2 O₂(g) → Na₄SiO₄(s)
Answer:

Explanation:
Hello!
In this case, since Helium is undergoing a volume-pressure change, according the Boyle's law, we infer the following equation is used:

Thus, since we are not given the volume at 0.25 atm, we can solve for V2 to do so:

Thus, we plug in to obtain:

Best regards!
Answer: The freezing point depression is 
Explanation:
Depression in freezing point is given by:
= Depression in freezing point
= freezing point constant =
m= molality =
Thus freezing point depression is 
When preparing diluted solutions from concentrated solutions , we can use the following equation;
c1v1 =c2v2
Where c1 and v1 are the concentration and volume of the concentrated solution
c2 is the concentration of the diluted solution to be prepared
v2 is the volume of the diluted solution
Substituting the values;
12.0 M x v1 = 0.339 M x 100 mL
v1 = 2.825 mL needs to be taken from the stock solution