JEE Advance - Chemistry (2000)

• 1

  A hydrogenation reaction is carried out at 500 K. If the same reaction is carried out in the presence of a catalyst at the same rate, the temperature required is 400 K. Calculate the activation energy of the reaction if the catalyst lowers the activation barrier by 20 kJ mol^-1.

  回答

  (C)

  80 kJ mol^-1
• 1

  The number of nodal planes in a p_x orbital is

  回答

  (A)

  one
• 2

  The following electrochemical cell has been set up.
  Pt(1) | Fe³⁺, Fe²⁺ (a = 1) | Ce⁴⁺, Ce³⁺ (a=1) | Pt(2)
  E^o (Fe³⁺, Fe²⁺) = 0.77 V; E^o (Ce⁴⁺, Ce³⁺) = 1.61 V
  If an ammeter is connected between the two platinum electrodes, predict the direction of flow of current. Will the current increase or decrease with time?

  回答

  (E)

  Cerium electrode to iron electrode, decrease
• 2

  Amongst the following identify the species with an atom in +6 oxidation state

  回答

  (D)

  $$Cr{O_2}C{l_2}$$
• 3

  Copper sulphate solution (250 mL) was electrolysed using platinum anode and a copper cathode. A constant current of 2mA was passed for 16 minutes. It was found that after electrolysis the absorbance of the solution was reduced to 50% of its original value. Calculate the concentration of copper sulphate in the solution to begin with.

  回答

  (C)

  7.96 x 10^-5 mol L^-1
• 3

  The electronic configuration of an element is 1s², 2s² 2p⁶, 3s² 3p⁶ 3d⁵, 4s¹ This represents its

  回答

  (B)

  ground state
• 4

  To 500 cm³ of water, 3.0 $$\times$$ 10^-3 kg of acetic acid is added. If 23% of acetic acid is dissociated, what will be the depression in freezing point? Kf and density of water are 1.86 K kg^-1 mol^-1 and 0.997 g cm^-3, respectively

  回答

  (C)

  0.228 K
• 4

  The correct order of radii is

  回答

  (B)

  F^- < O^2- < N^3-
• 5

  Write down the M.O. electron distribution of O₂. Specify its bond order and magnetic property.

  回答

  (A)

  σ2s²σ2s*²σ2p²π2p⁴π2p*², Bond order=2, Paramagnetic
• 5

  The correct order of acidic strength is

  回答

  (A)

  Cl₂O₇ > SO₂ > P₄O₁₀
• 6

  Calculate the energy required to excite one litre of hydrogen gas at 1 atm and 298 K to the first excited state of atomic hydrogen. The energy for the dissociation of H-H bond 436 kJ mol^-1.

  回答

  (D)

  98.32 kJ
• 6

  Amongst H₂O, H₂S, H₂Se and H₂Te, the one with the highest boiling point is

  回答

  (A)

  H₂O because of hydrogen bonding
• 7

  Read the following statement and explanation and answer as per the options given below
  
  ASSERTION : The first ionization energy of Be is greater than that of B.
  
  REASON : 2p orbital is lower in energy than 2s.

  回答

  (C)

  If assertion is CORRECT, but reason is INCORRECT
• 8

  Molecular shape of SF₄, CF₄ and XeF₄ are

  回答

  (D)

  different, with 1, 0 and 2 lone pairs of electrons respectively
• 9

  The hybridisation of atomic orbitals of nitrogen in $$NO_2^+$$, $$NO_3^-$$ and $$NH_4^+$$ are

  回答

  (B)

  sp, sp² and sp³ respectively