Answer 1

The equation of state is given by,

pV = nRT ……….. (i)

Where,

p → Pressure of gas

V → Volume of gas

n→ Number of moles of gas

R → Gas constant

T → Temperature of gas

From equation (i) we have,

`n/V = p/"RT"`

Replacing n with `m/M` we have

`m/(MV) = p/"RT"`   ...(ii)

Where,

m → Mass of gas

M → Molar mass of gas

But `m/V = d` (d = density of gas)

Thus, from equation (ii), we have

`d/M =  p/"RT"`

`=>d=(M/"RT")p`

Molar mass (M) of a gas is always constant and therefore, at constant temperature (T), `M/"RT"`= constant.

`d  = (constant)p`

`=>d prop p`

Hence, at a given temperature, the density (d) of gas is proportional to its pressure (p)

Answer 2

According to ideal gas equation

PV = nRT or PV=nRT/V

`n = "Constant Mass of gas"/"Molar mass of gas"`

`P = (mRT)/"MV"`           [`:. rho("density") = m/V`]

`P =  (rhoRT)/M`

`Pxx rho` at constant temperature