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
Answer: 1800 L
Explanation:
Given that,
Original pressure of gas (P1) = 180 kPa
Original volume of gas (V1) = 1500 L
New pressure of gas (P2) = 150 kPa
New volume of gas (V2) = ?
Since pressure and volume are given while temperature is held constant, apply the formula for Boyle's law
P1V1 = P1V2
180 kPa x 1500 L = 150 kPa x V2
270000 kPa•L = 150 kPa•V2
Divide both sides by 150 kPa
270000 kPa•L/150 kPa = 150 kPa•V2/150 kPa
1800L = V2
Thus, the new volume of the gas is 1800 liters.