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Which is the correct relation between change in enthalpy and change in internal energy?
$\Delta H = \Delta U + p\Delta V = \Delta U + \Delta n_g RT$.
Consider the following compounds/species:
i.
ii.
iii.
iv.
v.
vi.
vii.
The number of compounds/species which obey Huckel's rule is:
Aromatic (4n+2): naphthalene (10π), cyclopentadienyl anion (6π), cyclopropenyl cation (2π), anthracene (14π) → 4. Cyclobutadiene & cyclopropenyl anion are antiaromatic; cyclooctatetraene is non-planar.
The equilibrium concentrations of the species in the reaction $A + B \rightleftharpoons C + D$ are $2, 3, 10$ and $6\ \text{mol L}^{-1}$, respectively at 300 K. $\Delta G^\circ$ for the reaction is ($R = 2\ \text{cal mol}^{-1} \text{K}^{-1}$):
$K_c = \dfrac{10\times 6}{2\times 3} = 10$. $\Delta G^\circ = -RT\ln K_c = -2(300)(2.303) = -1381.8\ \text{cal}$.
Which of the following statements are INCORRECT?
A. All the transition metals except scandium form MO oxides which are ionic. B. The highest oxidation number corresponding to the group number in transition metal oxides is attained in Sc₂O₃ to Mn₂O₇. C. Basic character increases from V₂O₃ to V₂O₄ to V₂O₅. D. V₂O₄ dissolves in acids to give VO₄³⁻ salts. E. CrO is basic but Cr₂O₃ is amphoteric.
C wrong (basicity decreases as oxidation number rises). D wrong (V₂O₄ + acid gives $VO^{2+}$, not VO₄³⁻).
Given below are two statements:
Statement I: Aniline does not undergo Friedel-Crafts alkylation reaction.
Statement II: Aniline cannot be prepared through Gabriel synthesis.
In the light of the above statements, choose the correct answer from the options given below:
AlCl₃ complexes with –NH₂ lone pair, deactivating the ring (Statement I true). Gabriel synthesis gives primary aliphatic amines only — aryl halides do not undergo S$_\text{N}$2 with phthalimide ion (Statement II true).
Match List I with List II.
| List I (Compound) | List II (Shape/geometry) |
|---|---|
| A. NH₃ | I. Trigonal Pyramidal |
| B. BrF₅ | II. Square Planar |
| C. XeF₄ | III. Octahedral |
| D. SF₆ | IV. Square Pyramidal |
Choose the correct answer from the options given below:
NH₃ trigonal pyramidal; BrF₅ square pyramidal; XeF₄ square planar; SF₆ octahedral.
Match List I with List II.
| List I (Molecule) | List II (Number and types of bond/s between two carbon atoms) |
|---|---|
| A. ethane | I. one σ-bond and two π-bonds |
| B. ethene | II. two π-bonds |
| C. carbon molecule, C₂ | III. one σ-bond |
| D. ethyne | IV. one σ-bond and one π-bond |
Choose the correct answer from the options given below:
Ethane: single σ; Ethene: σ+π; C₂ in MO theory: two π (bond order 2); Ethyne: σ+2π.
For the reaction $2A \rightleftharpoons B + C$, $K_c = 4\times 10^{-3}$. At a given time, the composition of reaction mixture is: $[A] = [B] = [C] = 2\times 10^{-3}\,\text{M}$. Then, which of the following is correct?
$Q = [B][C]/[A]^2 = 1 > K_c$, so reaction proceeds backward to lower $Q$.
Match List I with List II.
| List I (Process) | List II (Conditions) |
|---|---|
| A. Isothermal process | I. No heat exchange |
| B. Isochoric process | II. Carried out at constant temperature |
| C. Isobaric process | III. Carried out at constant volume |
| D. Adiabatic process | IV. Carried out at constant pressure |
Choose the correct answer from the options given below:
Isothermal: constant T; Isochoric: constant V; Isobaric: constant P; Adiabatic: no Q.
Match List I with List II.
| List I (Quantum Number) | List II (Information provided) |
|---|---|
| A. $m_l$ | I. shape of orbital |
| B. $m_s$ | II. size of orbital |
| C. $l$ | III. orientation of orbital |
| D. $n$ | IV. orientation of spin of electron |
Choose the correct answer from the options given below:
$m_l$: orientation; $m_s$: spin orientation; $l$: shape; $n$: size.
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