JEE Advance - Chemistry (1994)

1
The composition of a sample of Wustite is Fe0.93O1.00 what percentage of the iron is present in the form of Fe(III)?
Answer
(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.
Answer
(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.
Answer
(A)
0.25 M, 0.24 m, 4.3 × 10-3
4
The outermost electronic configuration of Cr is _______.
Answer
(C)
3d5 4s1
5
Find out the number of waves made by a Bohr electron in once complete revolution in its 3rd orbit?
Answer
3
6
The two types of bond present in B2H6 are covalent and _______.
Answer
(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?
Answer
(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 27o 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 0o C.
Answer
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?
Answer
(C)
8 : 1
10
Complete and balance the following reactions:
Ca5(PO4)3F + H2SO4 + H2O $$\buildrel {Heat} \over \longrightarrow $$ ........ + 5CaSO4.2H2O + ........
Answer
(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.
Answer
(A)
Both S and E are true and E is the correct explanation of S
12
The IUPAC name of succinic acid is _______.
Answer
(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-; Eo = +0.40V
FeO(s) + H2O(l) + 2e- $$\leftrightharpoons$$ Fe(s) + 2OH-; Eo = -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?
Answer
(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, Ksp = 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.
Answer
(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.
Answer
(D)
A = KO2, B = K2SO4, C = K2SO4·Al2(SO4)3·24H2O