Answer:
The volume of the gas at a pressure of 65.0 kPa would be 363 mL
Explanation:
Boyle's Law is a gas law that relates the pressure and volume of a certain amount of gas, without temperature variation, that is, at constant temperature.
Boyle's law states that the pressure of a gas in a closed container is inversely proportional to the volume of the container, when the temperature is constant. In other words, the product P · V remains constant at the same temperature:
P*V=k
Being P1 and V1 the pressure and volume in state 1 and P2 and V2 the pressure and volume in state 2 are fulfilled:
P1*V1=P2*V2
In this case:
- P1= 45 kPa= 45,000 Pa (being 1 kPa=1,000 Pa)
- V1= 525 mL= 0.525 L (being 1 L=1,000 mL)
- P2= 65 kPa= 65,000 Pa
- V2= ?
Replacing:
45,000 Pa* 0.525 L= 65,000 Pa*V2
Solving:

V2=0.363 L=363 mL
<u><em>The volume of the gas at a pressure of 65.0 kPa would be 363 mL</em></u>
Answer:
The number of moles =

The number of molecules =

Explanation:
Volume of the sphere is given by :

here, r = radius of the sphere


Radius = 3 mm
r = 3 mm
1 mm = 0.01 dm (1 millimeter = 0.001 decimeter)
3 mm = 3 x 0.01 dm = 0.03 dm
r = 0.03 dm
<em>("volume must be in dm^3 , this is the reason radius is changed into dm"</em>
<em>"this is done because 1 dm^3 = 1 liter and concentration is always measured in liters")</em>



(1 L = 1 dm3)
Now, concentration "C"=
The concentration is given by the formula :

This is also written as,

moles
One mole of the substance contain "Na"(= Avogadro number of molecules)
So, "n" mole of substance contain =( n x Na )

Molecules =

molecules
26g --- 1 mol
56g --- X
X= 56/26 = 2,154 mol
959 ml = 959cm³ = 0,959dm³
C = n/V
C = 2,154/0,959
C = 2,246 mol/dm³