The boiling points of HF, HCl, HBr and HI follow the order from

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Phosphorus pentachloride dissociates as follows, in a closed reaction vessel,
PCl5 (g) ⇌ PCl3(g) + cl2(g)
If total pressure at equilibrium of the reaction mixture is P and degree of dissociation of PCl5 is x, the partial pressure of PCl3 will be

  • open parentheses fraction numerator straight x over denominator straight x plus 1 end fraction close parentheses straight P
  • open parentheses fraction numerator 2 straight x over denominator straight x plus 1 end fraction close parentheses straight P
  • open parentheses fraction numerator straight x over denominator straight x minus 1 end fraction close parentheses straight P
  • open parentheses fraction numerator straight x over denominator straight x minus 1 end fraction close parentheses straight P
556 Views

12.

The formation of the oxide ion O2-(g) requires first an exothermic and then an endothermic step as shown below
straight O space left parenthesis straight g right parenthesis space space plus straight e to the power of minus space straight O to the power of minus left parenthesis straight g right parenthesis space increment straight H to the power of straight o space equals space minus space 142 space kJ space mol to the power of negative 1 end exponent
straight O to the power of minus space left parenthesis straight g right parenthesis space space plus straight e to the power of minus straight O to the power of 2 minus end exponent space left parenthesis straight g right parenthesis increment straight H to the power of straight o space equals space 844 space kJ space mol to the power of minus space

  • Oxygen is more electronegative

  • O- ion has comparatively larger size than oxygen atom

  • O- ion will tend to resist the addition of another electron

  • O- ion will tend to resist the addition of another electron

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13.

As the temperature is raised from 20°C to 40°C, the average kinetic energy of neon atoms changes by a factor of which of the following?

  • 1/2

  • 2

  • 313/293

  • 313/293

163 Views

14.

In Vander Waals equation of state of the gas law, the constant ‘b’ is a measure of 

  • intermolecular repulsions

  • intermolecular collisions per unit volume

  • Volume occupied by the molecules

  • Volume occupied by the molecules

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15.

An ideal gas expands in volume from 1×10-3 m3 to 1×10-2 m3 at 300 K against a constant pressure of 1×105 Nm-2. The work done is

  • -900 J

  • 900 J

  • 2780 J

  • 2780 J

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16.

For same mass of two different ideal gases of molecular weights M1 and M2, Plots of log V vs log p at a given constant temperature are shown. Identify the correct option.

  • M1 > M2

  • M1 = M2

  • M1 < M2

  • Can be predicted only if temeperature is known


17.

Which of the following has the dimension if [ML0T-2]?

  • Coefficient of viscosity

  • Surface tension

  • Vapour pressure

  • Kinetic energy


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18.

The boiling points of HF, HCl, HBr and HI follow the order

  • HF> HCl > HBr > HI

  • HF> HI> HBr > HCl

  • HI> HBr > HCl> H

  • HCl > HF> HBr > HI


B.

HF> HI> HBr > HCl

Due to hydrogen bonding, HF shows highest boiling point. Therefore van der Waals'  force decide the boiling point. Larger the size or molecules mass, greater is the van der Waals' forces. Hence, higher is the boiling point.
·.· van der Waals' forces is more for HI than HBr, which is in turn is more than HCl.

Hence, correct order is HF > HI > HBr > HCl.


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19.

At a certain temperature, the value of the slope of the plot of osmotic pressure (π) against concentration (C in molL-1) of a certain polymer solution is 291R. The temperature at which osmotic pressure is measured, is (R is gas constant)

  • 271°C

  • 18°C

  • 564 K

  • 18 K


20.

For one mole of an ideal gas, the slope of V vs. T curve at constant pressure of 2 atm is X L mol-1 K-1.The value of the ideal universal gas constant 'R' in terms of X is

  • X L atm  mol-1 K-1

  • x/2 L atm  mol-1 K-1

  • 2X L atm  mol-1 K-1

  • 2X atm L-1 mol-1 K-1


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