In a 500 mL flask, the degree of dissociation of PCl5 at equilibr

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

An electronic transition in hydrogen atom results in the formation of Hα line of hydrogen in Lyman series, the energies associated with the electron in each of the orbits involved in the transition (in kcal mol-1) are 

  • -313,6, - 34.84

  • -313.6, - 78.4

  • -78.4,- 34.84

  • -78.4,-19.6


2.

The velocities of two particles A and B are 0.05 and 0.02 ms-1 respectively. The mass of B is five times the mass of A. The ratio of their de-Broglie's wavelength is

  • 2 : 1

  • 1 : 4

  • 1 : 1

  • 4 : 1


3.

The atomic numbers of elements A, B, C and D are Z - 1; Z; Z + 1 and Z + 2, respectively. If 'B' is a noble gas, choose the correct answers from the following statements-

1) 'A' has higher electron affinity.

(2) 'C' exists in +2 oxidation state. 

(3) 'D' is an alkaline earth metal.

  • (1) and (2)

  • (2) and (3)

  • (1) and (3)

  • (1), (2) and (3)


4.

The bond length of HCl molecule is 1.275 Å and its dipole moment is 1.03 D. The ionic character of the molecule (in percent) (charge of the electron = 4.8 × 10-10 esu) is

  • 100

  • 67.3

  • 33.66

  • 16.83


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5.

Which one of the following is a correct set ?

  • H2O, sp3, angular

  • BCl3, sp3, angular

  • NH4+, dsp2, square planar

  • CH4, dsp2, tetrahedral


6.

Match the following:
List - I List - II
A. 10 gm CaCO3 decomposition (i) 0.224 L CO2
B. 1.06 g Na2CO3 Excess HCl (ii) 4.48 L CO2
C. 2.4 g C CombustionExcess O2 (iii) 0.448 L CO2
D. 0.56 g CO combustionExcess O2

(iv) 2.24 L CO2

(v) 22. 4 L CO2

The correct match is

  • A - iv; B - i; C - ii; D - iii

  • A - v; B - i; C - ii; D - iii

  • A - iv; B - i; C - iii; D - ii

  • A - i; B - iv; C - ii; D - iii


7.

When 25 g of a non-volatile solute is dissolved in 100 g of water, the vapour pressure is lowered by 2.25 × 10-1 mm. If the vapour pressure of water at 20°C is 17.5 mm, what is the molecular weight of the solute ?

  • 206

  • 302

  • 350

  • 276


8.

50 mL of H2O is added to 50 mL of 1 × 10-3 M barium hydroxide solution. What is the pH of the resulting solution ?

  • 3.0

  • 3.3

  • 11.0

  • 11.7


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9.

For a crystal, the angle of diffraction (2 θ) is 90° and the second order line has a d value of 2.28 Å. The wavelength (in Å) of X-rays used for Bragg's diffraction is

  • 1.612

  • 2.00

  • 2.28

  • 4.00


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10.

In a 500 mL flask, the degree of dissociation of PCl5 at equilibrium is 40% and the initial amount is 5 moles. The value of equilibrium constant in mol L-1 for the decomposition of PCl5 is

  • 2.33

  • 2.66

  • 5.32

  • 4.66


B.

2.66

 Initial molesMoles at equilibriumConc. at equilibriumPCl555(1 - α)5(1 - α)0.5  PCl305α5α0.5 + Cl205α5α0.5

α = 40%

Kc = PCl3Cl2PCl5     = 5 × 0.40.55 × 0.40.55 × 0.60.5     =166

2.66 mol/ L


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