The relative lowering of vapour pressure of a dilute aqueous solu

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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1.

The relative lowering of vapour pressure of a dilute aqueous solution containing non-volatile solute is 0.0125. The molality of the solution is about

  • 0.70

  • 0.50

  • 0.90

  • 0.80


A.

0.70

Relative lowering of vapour pressure = mole fraction of solute (Raoult's Law)

p - psp = X2p - psp =wMmW

where, w = weight of solute

M = molecular weight of solvent

m = molecular weight of solute

W = weight of solvent

0.0125 = wMmW

or, wmW = 0.012518 = 0.00070

Hence, molarity = wmW× 1000

                       = 0.0007 × 1000

                       = 0.70


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2.

The activation energy of exothermic reaction A → B is 80 kJ mo1-1. The heat of reaction is 200 kJ mol-1. The activation evergy for the reaction B → A (in kJ mol-1) will be

  • 280

  • 200

  • 120

  • 40


3.

The strongest base among the following is

  • C6H5NH2

  • (C6H5)2NH

  • NH3

  • (C2H5)2NH


4.

The radius of the first Bohr orbit of hydrogen atom is 0.529 Å. The radius of the third orbit of H+ will be

  • 8.46 Å

  • 0.705 Å

  • 1.59 Å

  • 4.29 Å


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5.

Which diagram best represents the appearance of the line spectrum of atomic hydrogen in the visible region?


6.

Which of the following is paramagnetic with bond order 0.5?

  • F2

  • H2+

  • N2

  • O2-


7.

Match List-I with List-II and choose the correct matching codes from the choices given.
List - I List - II
A. PCl5 1. Linear
B. IF7 2. Pyramidal
C. H3O+ 3. Trigonal bipyramidal
D. ClO2 4. Tetrahedral
E. NH4+

5. Pentagonal bipyramidal

6. Angular

  • A - 3; B - 5; C - 2; D - 1; E - 4

  • A - 3; B - 5; C - 4; D - 1; E - 2

  • A - 3; B - 5; C - 6; D - 1; E - 2

  • A - 3; B - 5; C - 2; D - 6; E - 4


8.

Which one of the following volume (V)- temperature (T) plots represents the behaviour of one mole of an ideal gas at one atmospheric pressure?


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9.

In which one of the following pairs the radius of the second species is greater than that of the first?

  • Na, Mg

  • O2-, N3-

  • Li+, Be2+

  • Ba2+, Sr2+


10.

Match List-I with List-II Choose the correct matching codes from the choices given.
List - I (Hydride) List - II (Type of hydride)
A. BeH2 1. Complex
B. AsH3 2. Lewis acid
C. B2H6 3. Interstitial
D. LaH3 4. Covalent
E. LiAlH4

5. Intermediate

6. Ionic

  • A - 6; B - 2; C - 4; D - 5; E - 1

  • A - 5; B - 4; C - 2; D - 3; E - 1

  • A - 6; B - 4; C - 2; D - 3; E - 5

  • A - 6; B - 4; C - 2; D - 3; E - 1


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