The addition of a catalyst during a chemical reaction alters which of the following quantities?
a.
Internal energy
b.
Enthalpy
c.
Activation energy
Correct Answer
d.
Entropy
Step-by-Step AI Explanation
Verified Method
A catalyst provides an alternative reaction pathway with a lower activation energy, thereby increasing the rate of reaction without changing the internal energy, enthalpy, or entropy of the system.
Q2mcq
Predict the correct order of repulsion among the following:
According to VSEPR theory, lone pair electrons occupy more space around the central atom than bond pair electrons, leading to the order of repulsion: lone pair-lone pair > lone pair-bond pair > bond pair-bond pair.
Q3mcq
The correct statement regarding the basicity of arylamines is:
a.
Arylamines are generally more basic than alkylamines because the nitrogen lone-pair electrons are not delocalized by interaction with the aromatic ring π electron system.
b.
Arylamines are generally more basic than alkylamines because of the aryl group.
c.
Arylamines are generally more basic than alkylamines, because the nitrogen atom in arylamines is sp-hybridized.
d.
Arylamines are generally less basic than alkylamines because the nitrogen lone-pair electrons are delocalized by interaction with the aromatic ring π electron system.
Correct Answer
Step-by-Step AI Explanation
Verified Method
In arylamines, the lone pair on the nitrogen atom is delocalized into the aromatic ring via resonance, making it less available for protonation compared to alkylamines where the lone pair is localized.
Q4mcq
When copper is heated with conc. HNO3 it produces:
a.
Cu(NO3)2 and NO
b.
Cu(NO3)2, NO and NO2
c.
Cu(NO3)2 and N2O
d.
Cu(NO3)2 and NO2
Correct Answer
Step-by-Step AI Explanation
Verified Method
Copper reacts with concentrated nitric acid to produce copper(II) nitrate, water, and reddish-brown nitrogen dioxide gas: Cu + 4HNO3 → Cu(NO3)2 + 2H2O + 2NO2.
Q5mcq
For the following reactions: (a) CH3CH2CH2Br + KOH → CH3CH=CH2 + KBr + H2O, (b) (CH3)2CHBr + KOH → (CH3)2CHOH + KBr, (c) CH2=CH2 + Br2 → CH2BrCH2Br. Which of the following statements is correct?
a.
(a) is elimination, (b) is substitution and (c) addition reaction.
Correct Answer
b.
(a) is elimination, (b) and (c) are substitution reactions.
c.
(a) is substitution, (b) and (c) are addition reactions.
d.
(a) and (b) are elimination reactions and (c) is addition reaction.
Step-by-Step AI Explanation
Verified Method
Reaction (a) is a dehydrohalogenation (elimination), (b) is a nucleophilic substitution of Br by OH, and (c) is an electrophilic addition of bromine across the double bond.
Q6mcq
Two electrons occupying the same orbital are distinguished by:
a.
Magnetic quantum number
b.
Azimuthal quantum number
c.
Spin quantum number
Correct Answer
d.
Principal quantum number
Step-by-Step AI Explanation
Verified Method
According to the Pauli exclusion principle, no two electrons in an atom can have the same four quantum numbers. Since they are in the same orbital (n, l, and ml are the same), they must differ in their spin quantum number (ms).
Q7mcq
The reaction of an alkoxide with an alkyl halide (e.g., Na+O-R + R'-X → R-O-R' + NaX) can be classified as:
It is the Williamson ether synthesis reaction, which involves the reaction of an alkoxide (R-ONa) with an alkyl halide (R-X) to form an ether (R-O-R) and a salt (NaX).
Q8mcq
The electronic configurations of Eu (Atomic No. 63), Gd (Atomic No. 64) and Tb (Atomic No. 65) are:
a.
[Xe]4f6 5d1 6s2, [Xe]4f7 5d1 6s2 and [Xe]4f9 6s2
b.
[Xe]4f6 5d1 6s2, [Xe]4f7 5d1 6s2 and [Xe]4f8 5d1 6s2
c.
[Xe]4f7 6s2, [Xe]4f7 5d1 6s2 and [Xe]4f9 6s2
Correct Answer
d.
[Xe]4f7 6s2, [Xe]4f8 6s2 and [Xe]4f8 5d1 6s2
Step-by-Step AI Explanation
Verified Method
Eu (63) is [Xe]4f7 6s2 (half-filled f-subshell is stable), Gd (64) is [Xe]4f7 5d1 6s2 (extra stability of half-filled f-subshell), and Tb (65) is [Xe]4f9 6s2.
Q9mcq
At 100ºC the vapour pressure of a solution of 6.5 g of a solute in 100 g water is 732 mm. If Kb = 0.52, the boiling point of this solution will be:
a.
100ºC
b.
102ºC
c.
103ºC
d.
101ºC
Correct Answer
Step-by-Step AI Explanation
Verified Method
Using Raoult's Law (P0 - Ps)/P0 = n2/(n1 + n2) ≈ n2/n1, molality m is calculated as 2.125. Then ΔTb = Kb * m = 0.52 * 2.125 ≈ 1.10. Boiling point = 100 + 1.10 = 101.1ºC, closest to 101ºC.
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Match the compounds given in column I with the hybridisation and shape given in column II and mark the correct option. (a) XeF6 (b) XeO3 (c) XeOF4 (d) XeF4
a.
(a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)
b.
(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
c.
(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
d.
(a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)
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The correct statement regarding a carbonyl compound with a hydrogen atom on its alpha-carbon, is:
a.
a carbonyl compound with a hydrogen atom on its alpha-carbon rapidly equilibrates with its corresponding enol and this process is known as aldehyde-ketone equilibration.
b.
a carbonyl compound with a hydrogen atom on its alpha-carbon rapidly equilibrates with its corresponding enol and this process is known as carbonylation.
c.
a carbonyl compound with a hydrogen atom on its alpha-carbon rapidly equilibrates with its corresponding enol and this process is known as keto-enol tautomerism.
d.
a carbonyl compound with a hydrogen atom on its alpha-carbon never equilibrates with its corresponding enol.
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Match items of Column I with the items of Column II and assign the correct code:
Column I Column II
(a) Cyanide process (i) Ultrapure Ge
(b) Froth floatation process (ii) Dressing of Zns
(c) Electrolytic reduction (iii) Extraction of Al
(d) Zone refining (iv) Extraction of Au
(v) Purification of Ni
a.
(1) (ii) (iii) (i) (v)
b.
(2) (i) (ii) (iii) (iv)
c.
(3) (iii) (iv) (v) (i)
d.
(4) (iv) (ii) (iii) (i)
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Which of the following statements about the composition of the vapour over an ideal 1 : 1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at 25ºC. (Given, Vapour Pressure Data at 25ºC, benzene = 12.8 kPa, toluene = 3.85 kPa)
a.
The vapour will contain a higher percentage of toluene
b.
The vapour will contain equal amounts of benzene and toluene
c.
Not enough information is given to make a prediction
d.
The vapour will contain a higher percentage of benzene
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MY and NY3, two nearly insoluble salts, have the same KSP values of 6.2 × 10^-13 at room temperature. Which statement would be true in regard to MY and NY3?
a.
The molar solubility of MY in water is less than that of NY3
b.
The salts MY and NY3 are more soluble in 0.5 M KY than in pure water
c.
The addition of the salt of KY to solution of MY and NY3 will have no effect on their solubilities
d.
The molar solubilities of MY and NY3 in water are identical
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Consider the nitration of benzene using mixed conc. H2SO4 and HNO3. If a large amount of KHSO4 is added to the mixture, the rate of nitration will be :
a.
slower
b.
uncharged
c.
doubled
d.
faster
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The rate of a first order reaction is 0.04 mol l⁻¹ s⁻¹ at 10 seconds and 0.03 mol l⁻¹ s⁻¹ at 20 seconds after initiation of the reaction. The half-life period of the reaction is :
a.
34.1 s
b.
44.1 s
c.
54.1 s
d.
24.1 s
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The rate of a first order reaction is 0.04 mol l^-1 s^-1 at 10 seconds and 0.03 mol l^-1 s^-1 at 20 seconds after initiation of the reaction. The half-life period of the reaction is:
a.
34.1 s
b.
44.1 s
c.
54.1 s
d.
24.1 s
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