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 Multiple Choice QuestionsMultiple Choice Questions

31.

0.1 mol HCl is equal to

  • 3.65 g

  • 36.5 g

  • 18 g

  • 1.8 g


32.

A 0.5 g/L solution of glucose is found to be isotonic with a 2.5 g/L solution of an organic compound. What will be the molecular weight of that organic compound ?

  • 300

  • 600

  • 900

  • 200


33.

The pH of a 0.001 M solution of HCl is

  • 0

  • 3

  • 5

  • 10


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34.

The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass Al= 27)

  • 180 kg

  • 270 kg

  • 540 kg

  • 90 kg


D.

90 kg

In Hall and Heroult process

2Al2O3  4Al + 3O2

4C + 3O2  2CO2 + 2CO 

2Al2O3 + 4C 4Al + 2CO2 + 2CO

Only for removal of CO2, following equation is possible

2Al2O3 + 3C 4Al + 3CO2

Molecular weight of Carbon = 12

Molecular weight of Aluminium = 27

 For Carbon/ C = 3 x 12 = 36

    For Aluminium/ Al = 4 x 27 = 108

 For 108 gm of Al, 36 gm of C is required in above reaction

 For 270 gm of Al require amount of C = 36108 × 270 =90 gm


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35.

The number of moles of KMnO4 reduced by one mole of KI in alkaline medium is

  • one-fifth

  • five

  • one

  • two


36.

A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressure of the pure hydrocarbons at 20°C are 440 mm of Hg for pentane and 120 mm of Hg for hexane. The mole fraction of pentane in the vapour phase would be

  • 0.549

  • 0.200

  • 0. 786

  • 0.478


37.

If for a sucrose solution, elevation in boiling point is 0.1°C, then what will be the boiling point of NaCl solution for same molal concentration ?

  • 0.1°C

  • 0.2°C

  • 0.08°C

  • 0.01°C


38.

The vapour pressure of pure water is 25.0 mm Hg and that of an aqueous dilute solution of urea in 20mm Hg at 25°C. The molarity of the solution is:

  • 12.6

  • 14.9

  • 13.8

  • 9.6


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39.

The significant figures in 1.0024, 1.240 and 0.0020 are respectively

  • 5, 4, 2

  • 3, 3, 1

  • 5, 3, 4

  • 5, 3, 2


40.

A cylinder of compressed gas contains nitrogen and oxygen in the ratio of 3:1 by mole. The total mass of the gas mixture if the cylinder is known to contain 2.5 x 10g of oxygen will be:

  • 8 x 103 g

  • 9 x 10g

  • 9 x 103 g

  • 8 x 102 g


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