Answer:
idvd has a very high performance and a lot more than just the right side to get it all out
Answer : The pressure of the helium gas is, 1269.2 mmHg
Explanation :
To calculate the pressure of the gas we are using ideal gas equation:

where,
P = Pressure of
gas = ?
V = Volume of
gas = 210. mL = 0.210 L (1 L = 1000 mL)
n = number of moles
= 0.0130 mole
R = Gas constant = 
T = Temperature of
gas = 
Putting values in above equation, we get:


Conversion used : (1 atm = 760 mmHg)
Thus, the pressure of the helium gas is, 1269.2 mmHg
Answer:
See explanation
Explanation:
1) Physical change is usually reversible, while chemical change isn't
2) Chemical change involves the change of chemical composition of matter while physical change doesn't
This is a dilution that requires a certain volume from the stock solution to be diluted with distilled water to make a solution of HBr with a lesser concentration than the stock solution
Following dilution formula can be used
c1v1 = c2v2
Where c1 is concentration and v1 is the volume of the stock solution
c2 is concentration and v2 is volume of the diluted solution to be prepared
Substituting these values
10.0 M x v1 = 3.0 x 450.0 mL
v1 = 135.0 mL
A volume of 135.0 mL from HBr stock solution needs to be taken and diluted with distilled water upto 450.0 mL. The resulting solution will have a concentration of 3.0 M