Physics MCQs for NEET — Practice Questions with Answers

(d) The units of 'a; are: atm litre² mol^-2

                                = atm dm⁶mol^-2 = dyne cm²mol^-2

     The units of 'b' are: litre mol^-1 = dm³mol^-1 = cm³mol^-1

(d) This is one of the limitation of vander Waal's equation.

'a' is measure of force, which is sensitive for distance, with increase in temp, the distance between molecule increase,so magnitude of force decrease. 'b' is measure of size, which is not so sensitive as 'a'   . but it also changes.

(c) At high pressure, volume of molecules should not be neglected in comparison to volume of gas. Also experimental to volume of gas. Also, experimental studies reveals PV > RT at high P.

(a) Ideal gas does not show Joule-Thomson effect.

(d) a=P x V² = atm litre² mol-² = dyne cm⁴ mol^-2 = Newton m⁴ mol^-2 = atm dm⁶ mol^-2

(d) b = 4Nv;   unit of b = litre mol^-1 = cm³ mol^-1 = m³ mol^-1

(d) Gases can be liquefied by lowering the temperature and increasing the pressure. An ideal gas have no intermolecular force of attraction, so it cannot be liquefied by applying high pressure and decreasing temperature.

(a) For H₂ and He, PV > nRT; Also Z = PV/nRT .

(d) Root mean square velocity at T₁ temperature,

              U₁ = $\sqrt{\frac{3R{T}_1}{M}}=\sqrt{\frac{3R(27+273)}{M}}$            .....(i)

    Root mean square velocity at T₂ temperature,

             U₂ = $\sqrt{\frac{3R{T}_2}{M}}=\sqrt{\frac{3R(927+273)}{M}}$           ......(ii)

      Eq. (i) divided by Eq. (ii)

             U₁/U₂ = $\sqrt{\frac{27 +273}{927 + 273}}$= $\sqrt{\frac{300}{1200}}$=1/2

                  U₂ = 2U₁