JEE Advance - Chemistry (1994)

• 1

  The composition of a sample of Wustite is Fe_0.93O_1.00 what percentage of the iron is present in the form of Fe(III)?

  回答

  (C)

  15.05%
• 2

  The compound YBa₂Cu₃O₇, which shows superconductivity, has copper in oxidation state ______ assume that the rare earth element yttrium is in its usual +3 oxidation state.

  回答

  (B)

  +7/3
• 3

  8.0575 $$\times$$ 10^-2 kg of Glauber's salt is dissolved in water to obtain 1 dm³ of a solution of density 1077.2 kg.m^-3. Calculate the molarity, molality and mole fraction Na₂SO₄ in the solution.

  回答

  (A)

  0.25 M, 0.24 m, 4.3 × 10^-3
• 4

  The outermost electronic configuration of Cr is _______.

  回答

  (C)

  3d⁵ 4s¹
• 5

  Find out the number of waves made by a Bohr electron in once complete revolution in its 3rd orbit?

  回答

  3
• 6

  The two types of bond present in B₂H₆ are covalent and _______.

  回答

  (E)

  Three-centered two-electron
• 7

  Using the VSEPR theory, identify the type of hybridization and draw the structure of OF₂. What are the oxidation states of O and F?

  回答

  (A)

  sp³, bent, O(+2), F(-1)
• 8

  An LPG (liquefied petroleum gas) cylinder weighs 14.8 kg when empty. When full, it weighs 29.0 kg and shows a pressure of 2.5 atm. In the course of use at 27^o C, the weight of the full cylinder reduces to 23.2 kg. Find out the volume of the gas in cubic meters used up at the normal usage conditions find the final pressure inside the cylinder. Assume LPG to be n-butane with normal boiling point of 0^o C.

  回答

  A

  D
• 9

  A 4 : 1 molar mixture of He and CH₄ is contained in a vessel at 20 bar pressure. Due to a hole in the vessel the gas mixture leaks out. What is the composition of the mixture effusing out initially?

  回答

  (C)

  8 : 1
• 10

  Complete and balance the following reactions:
  Ca₅(PO₄)₃F + H₂SO₄ + H₂O $$\buildrel {Heat} \over \longrightarrow $$ ........ + 5CaSO₄.2H₂O + ........

  回答

  (A)

  3H₃PO₄, HF
• 11

  Statement (S) The alkali metals can form ionic hydrides which contain the hydride ion H^-.
  Explanation (E) The alkali metals have low electronegativity; their hydrides conduct electricity when fused and liberate hydrogen at the anode.

  回答

  (A)

  Both S and E are true and E is the correct explanation of S
• 12

  The IUPAC name of succinic acid is _______.

  回答

  (C)

  butane-1,4-dioic acid
• 13

  The Edison storage cells is represented as
  Fe(s) | FeO(s) | KOH (aq) | Ni₂O₃(s) | Ni(s)
  The half-cell reactions are:
  Ni₂O₃ + H₂O (l) + 2e^- $$\leftrightharpoons$$ 2NiO(s) + 2OH^-; E^o = +0.40V
  FeO(s) + H₂O(l) + 2e^- $$\leftrightharpoons$$ Fe(s) + 2OH^-; E^o = -0.87V
  (i) What is the cell reaction?
  (ii) What is the cell e.m.f? How does it depend on the concentration of KOH?
  (iii) What is the maximum amount of electrical energy that can be obtained from one mole of Ni₂O₃?

  回答

  (E)

  Cell reaction: $$Fe(s) + Ni_2O_3(s) \rightleftharpoons FeO(s) + 2NiO(s)$$, Cell e.m.f: 1.27 V, Independent of KOH concentration, Maximum electrical energy: 245.11 kJ
• 14

  The standard reduction potential of the Ag⁺/Ag electrode at 298 K is 0.799V. Given that for AgI, K_sp = 8.7 $$\times$$ 10^-17, evaluate the potential of the Ag⁺/Ag electrode in a saturated solution of AgI. Also calculate the standard reduction potential of the I^-/ AgI/Ag electrode.

  回答

  (B)

  0.325 V, -0.148 V
• 15

  A is binary compound of a univalent metal. 1.422 g of A reacts completely with 0.321 g of sulphur in an evacuated and sealed tube to give 1.743 g of a white crystalline solid B, that forms a hydrated double salt, C with Al₂ (SO₄)₃ . Identify A, B and C.

  回答

  (D)

  A = KO2, B = K2SO4, C = K2SO4·Al2(SO4)3·24H2O