Class 11th

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option (ii) Nsm^-2 

viscosity coefficient (η) = $\frac{Force}{Area*VelocityGradient}$

SI unit of (η)= Nsm^-2

This is a multiple choice answer as classified in NCERT Exemplar

Option (iv) O₂, N₂, H₂, He

Higher the critical temperature of gases more easily, the gas will be liquefied. So, the order of liquefying of gases will be  O₂ > N₂ > H₂ >He. 

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Option (i) increases

Gay Lussac's law shows the direct relationship between the pressure and the temperature of a fixed amount of gas at constant volume.

Gay Lussac's law states that at constant volume, the pressure of a fixed amount of a gas is directly proportional to the temperature.

Therefore,  

P∝T   ……….at constant volume

Thus, pressure increases if the temperature is increased at a constant volume.

To elaborate more on this topic, we will see a real-life example.

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option (iii) 8 * 10⁴  Nm^-2 

Partial pressure of oxygen, Po₂= Xo₂   $*$ P_total

Mole fraction of O₂= $\frac{Moleofoxygen}{Molesofoxygen+Molesofhydrogen}$

= $\frac{4}{4+1}$ = $\frac{4}{5}$

Po₂= $\frac{4}{5}$ $*$ 1 = $\frac{4}{5}$  (?P_total = 1 atm)

1 atm =  1.1034 * 10⁵ Nm^-2 or Pa

Partial pressure of dioxygen = 0.8 *10⁵ = 8*10⁴  Nm^-2 

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option (iii) less than unit electronic charge 

Charge of 1 electron is 1.6 * 10 ^-19 C and the partial charge is always less than the unit electronic charge.

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option (iii) polarisability of interacting particles.

The energy of the London force or London dispersion force  is inversely proportional to (distance between two interacting particles)⁶ but their magnitude depends upon the polarisability of interacting particles.

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option  iii. p₁  < p₂ < p₃ < p₄

At a particular temperature, PV is constant

Therefore,   V ∝ $\frac{1}{\mathit{p}}$

So, as v₁ >  v₂  >  v₃  >  v₄   the order of pressure:  p₁  < p₂ < p₃ < p₄ .

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option (ii) surface tension 

Surface tension minimises the surface area of the liquid and at  minimum surface area, the liquid is in its the lowest energy state and hence most stable. Spherical shape of rain droplets has minimum surface area due to surface tension. 

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Option (iii) pressure decreases 

At high altitude the pressure is low and therefore, water boils at lower temperature because the vapour pressure becomes equal to atmospheric temperature at low temperature due to which the food takes more time to be cooked without using a pressure cooker.