Vapour pressure of benzene at 30°C is 121.8 mm. When 15 g of

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 Multiple Choice QuestionsMultiple Choice Questions

591.

The mixture ofconcentrated HCl and HNO3 made in 3 : 1 ratio contains

  • ClO2

  • NOCl

  • NCl3

  • N2O4


592.

The average osmotic pressure of human blood is 7.8 bar at 37°C. What is the concentration of an aqueous NaCl solution that could be used in the blood stream?

  • 0.16 mol/L

  • 0.32 mol/L

  • 0.60 mol/L

  • 0.45 mol/L


593.

Which one of the statements given below concerning properties of solutions, describes a colligative effect?

  • Boiling point of pure water decreases by the addition of ethanol.

  • Vapour pressure of pure water decreases by the addition of nitric acid.

  • Vapour pressure of pure benzene decreases by the addition of naphthalene.

  • Boiling point of pure benzene increases by the addition of toluene.


594.

Which one of the following is not a buffer solution?

  • 0.8M H2S + 0.8M KHS

  • 2M C6H5NH2 + 2M C6H5NH3-Br-

  • 3M H2CO3 + 3M KHCO3

  • 0.05M KClO4 + 0.05M HClO4


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595.

In aqueous alkaline solution, two electrons reduction of HO2- gives

  • HO-

  • H2O

  • O2

  • O2-


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596.

Vapour pressure of benzene at 30°C is 121.8 mm. When 15 g of a non-volatile solute is dissolved in 250 g of benzene, its vapour pressure is decreased to 120.2 mm. The molecular weight of the solute is

  • 35.67 g

  • 356.7 g

  • 432.8 g

  • 502. 7 g


B.

356.7 g

Relative lowering of vapour pressure is given by:

                      P°-PP°=w/mw/m +W/M

Where, P°= Vapour pressure of pure solvent

           P = Vapour pressure of solution 

           w = mass of solute

           m = molecular of solute

           W = mass of solvent

           M = molecular mass of solvent

For dilute solution

121.8 - 120.2121.8= 15/m250/78m = 356.265


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597.

58.4 g of NaCl and 180 g of glucose were separately dissolved in l000mL of water. Identify the correct statement regarding the elevation of the boiling point (b.p) of the resulting solutions.

  • NaCl solution will show higher elevation of boiling point

  • Glucose solution will show higher elevation of boiling point

  • Both the solutions will show equal elevation of boiling point

  • The boiling point elevation will be shown by neither of the solutions


598.

Which of the following will show a negative deviation from Raoult's law?

  • Acetone-benzene

  • Acetone-ethanol

  • Benzene-methanol

  • Acetone-chloroform


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599.

To observe an elevation of boiling point of 0.05°C, the amount of a solute (mol. wt. = 100) to be added to 100 g of water (Kb = 0.5) is

  • 2 g

  • 0.5 g

  • 1 g

  • 0.75 g


600.

Solubility product of Mg(OH)2 at ordinary temperature is 1.96 × 10-11 pH of a saturated solution of Mg(OH)2 will be

  • 10.53

  • 8.47

  • 6.94

  • 3.47


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