JEE Advance - Chemistry (1998)

• 1

  An aqueous solution containing 0.10 g KIO₃ (formula weight = 214.0) was treated with an excess of KI solution. The solution was acidified with HCl. The liberated I₂ consumed 45.0 mL of thiosulphate solution to decolourise the blue strach-iodine complex. Calculate the molarity of the sodium thiosulphate solution.

  回答

  (D)

  0.0623 M
• 2

  The orbital diagram in which the Aufbau principle is violated is

  回答

  (B)

  
• 3

  Interpret the non-linear shape of H₂S molecule and non-planar shape of PCl₃ using valence shell electron pair repulsion (VSEPR) theory. (Atomic numbers : H = 1, P = 15, S = 16, Cl = 17)

  回答

  A

  B

  C
• 4

  The rate constant of a reaction is 1.5 $$\times$$ 10⁷ s^-1 at 50^oC and 4.5 $$\times$$ 10⁷ s^-1 at 100^oC. Evaluate the Arrhenius parameters A and E_a.

  回答

  (A)

  A = 5.42 × 10¹⁰ s^-1, E_a = 2.2 × 10⁴ J mol^-1
• 5

  Find the solubility product of a saturated solution of Ag₂CrO₄ in water at 298 K if the emf of the cell Ag|Ag⁺ (satd. Ag₂CrO₄ soln.) || Ag⁺ (0.1 M) | Ag is 0.164 V at 298 K.

  回答

  (C)

  2.287 x 10^-12
• 6

  Calculate the equilibrium constant for the reaction:
  2Fe³⁺ + 3I^- $$\leftrightharpoons$$ 2Fe²⁺ + $$I_3^-$$. The standard reduction potentials in acidic conditions are 0.78 V and 0.54 V respectively for Fe³⁺ | Fe²⁺ and $$I_3^-$$ | I^- couples.

  回答

  (C)

  10⁸
• 7

  A solution of a nonvolatile solute in water freezes at -0.30^oC. The vapour pressure of pure water at 298 K s 23.51 mm Hg and K_f for water is 1.86 K kg mol^-1. Calculate the vapour pressure of this solution at 298 K.

  回答

  (D)

  23.44 mm Hg
• 8

  Hydrogen peroxide acts both as an oxidising and as a reducing agent in alkaline solution towards certain first row transition metal ions. Illustrate both these properties of H₂O₂ using chemical equations.

  回答

  (D)

  H₂O₂ can act as both an oxidizing and reducing agent in alkaline solutions, depending on the reactant.
• 9

  Work out the following using chemical equation :
  Chlorination of calcium hydroxide produces bleaching powder.

  回答

  (A)

  Ca(OH)₂ + Cl₂ → Ca(OCl)₂ + H₂O
• 10

  Highly pure dilute solution of sodium in liquid ammonia

  回答

  A

  B
• 11

  Read the following Assertion and Reason and answer as per the options given below
  
  Assetion: LiCl is predominantly a covalent compound
  
  Reason : Electronegativity difference between Li and Cl is too small

  回答

  (C)

  If assertion is correct but reason is incorrect
• 12

  The geometry and the type of hybrid orbital present about the central atom in BF₃ is

  回答

  (B)

  trigonal planar, sp²
• 13

  ASSERTION:
  Nuclide $${}_{13}^{30}Al$$ is less stable than $${}_{20}^{40}Ca$$
  
  REASON:
  Nuclides having odd number of protons and neutrons are generally unstable.

  回答

  (C)

  If assertion is correct but reason is incorrect.
• 14

  Which of the following statement(s) is (are) correct?

  回答

  A

  B

  C
• 15

  Decrease in atomic number is observed during

  回答

  A

  C

  D
• 16

  The energy of an electron in the first Bohr orbit of H atom is -13.6 eV. The possible energy value(s) of the excited state(s) for electrons in Bohr orbits of hydrogen is (are)

  回答

  (A)

  -3.4 eV