I need a little help on my chem. homework i dont understand this ?

Hi!

PV = nRT

This equation basically means at a given amount of pressure a gas contained in a certain volume for a specific amount of gas at kelvin temperature the ideal gas law can apply.

now the temperature and pressure is at constant.

Means you can cancel out P and T from both sides of the equation because they remain the same

So you get

v = nR

Now r is a constant used for calculation purposes.

So we don't need to write the r there

We can say

V = n

Now what does this mean? Volume = moles? Well technically yes. But avogadro's law states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules/ moles.

So now since pressure and temperature is constant we can simply write this as V=n where the equal volume of gases equal contain equal number of moles.

V/n = K

K is constant to show that pressure and temperature are constant.

Hope it helps!

Its just basically cancelling out P and T since it is said in the question it is constant, and R doesn't need to be there. So you can Say volume of Gases contan equal number of moles. or

V/ n = Volume of equal gases per equal mole at constant pressure and temperature is avogadro's law. I am sorry if i didn't answer you question well. Its hard to explain the whole theory. Hope it helps!