81.

Air at sea level is dense. This is a practical implimentation of :

• Boyle's law

• Charles' law

• Avogadro's law

• Dalton's law

The r.m.s. velocity of CO₂ at a temperature T (in kelvin) is x cm s^-1. At what temperature (in kelvin), the r.m.s. velocity of nitrous oxide would be 4x cm s^-1? (Atomic weights of C, N and O are respectively 12, 14 and 16)

• 16 T

• 2 T

• 4 T

• 32 T

n moles of an ideal gas at temperature T (in kelvin) occupy V L of volume, exerting a pressure of P atmospheres. What is the concentration (in mol/L) ?

• $\frac{\mathrm{P}}{\mathrm{RT}}$

• $\frac{\mathrm{PT}}{\mathrm{R}}$

• $\frac{\mathrm{RT}}{\mathrm{P}}$

• $\frac{\mathrm{R}}{\mathrm{PT}}$

4 g of an ideal gas occupies 5.6035 L of volume at 546 K and 2 atmosphere pressure. What is its molecular weight?

• 4

• 16

• 32

• 64

If a gas contains only three molecules that move with velocities of 100, 200, 500 ms^-1. What is the rms velocity of that gas in ms^-1?

• 100$\frac{\sqrt{8}}{3}$

• 100√30

• 100√10

• 800/3

If the electron of a hydrogen atom is present in the first orbit, the total energy of the electron is

• $\frac{-{\mathrm{e}}^2}{\mathrm{r}}$

• $\frac{-{\mathrm{e}}^2}{{\mathrm{r}}^2}$

• $\frac{-{\mathrm{e}}^2}{2\mathrm{r}}$

• $\frac{-{\mathrm{e}}^2}{2{\mathrm{r}}^2}$

At 27°C, a closed vessel contains a mixture of equal weights of helium (mol. wt. = 4), methane (mol, wt. = 16) and sulphur dioxide (mol. wt. = 64). The pressure exerted by the mixture is 210 mm. If the partial pressures of helium, methane and sulphur dioxide are p₁, p₂ and p₃ respectively, which one of the following is correct?

• p₃ > p₂ > p₁

• p₁ > p₂ > p₃

• p₁ > p₃ > p₂

• p₂ > p₃ > p₁

At 27°C, 500 mL of helium diffuses in 30 minutes. What is the time (in hours) taken for 1000 mL of SO₂ to diffuse under same experimental conditions?

• 240

• 3

• 2

• 4

A and B are ideal gases. The molecular weights of A and B are in the ratio of 1 :4. The pressure of a gas mixture containing equal weights of A and B is P atm. What is the partial pressure (in atm) of B in the mixture?

• P/5

• P/2

• P/2.5

• 3P/4

Which of the following set of variables give a straight line with a negative slope when plotted? (P = vapour pressure ; T = Temperature in K)

• y - axis	x - axis
  P	T

• log10 P

  T

• log10 P

  $\frac{1}{\mathrm{T}}$

• log10 P

  log10 $\frac{1}{\mathrm{T}}$