The increasing order of nucleophilicity of the following nucleophiles is : (a) (b) (c) (d)
1
2
3
4
Official Solution
Correct Option: (1)
ione pair donating tendency on oxygen is reduced, nucleophilicity reduced b < c < a < d
02
PYQ 2022
hard
chemistryID: jee-main
20 mL of 0.1 M NH4OH is mixed with 40 mL of 0.05 M HCl.The pH of the mixture is nearest to(Given :Kb(NH4OH) = 1Γ10β5,log2 = 0.30,log3 = 0.48, log5 = 0.69,log7 = 0.84,log11 = 1.04)
1
3.2
2
4.2
3
5.2
4
6.2
Official Solution
Correct Option: (3)
β΄ In final solution 2 millimoles of NH4Cl is present.
03
PYQ 2022
easy
chemistryID: jee-main
The oxidation state of manganese in the product obtained in a reaction of potassium permanganate and hydrogen peroxide in basic medium is____.
Official Solution
Correct Option: (1)
04
PYQ 2022
medium
chemistryID: jee-main
The reagent, from the following, which converts benzoic acid to benzaldehyde in one step is
1
2
3
4
Official Solution
Correct Option: (1)
The correct answer is (A) :
Fig. Chemical Reaction
05
PYQ 2022
medium
chemistryID: jee-main
For the reaction H2F2(g) β H2(g) + F2(g), ΞU = β59.6 kJ molβ1 at 27Β°C. The enthalpy change for the above reaction is (β) _______ kJ molβ1 [nearest integer] Given: R = 8.314 J Kβ1 molβ1.
Official Solution
Correct Option: (1)
H2F2(g) β H2(g) + F2(g) ΞU = -59.6 kJ mol-1 at C ΞH = ΞU +ΞngRT
=-59.6+
06
PYQ 2022
medium
chemistryID: jee-main
The number of non-ionisable protons present in the product B obtained from the following reactions is__. C2H5OH+PCl3βC2H5Cl+A A+PCl3βB
Official Solution
Correct Option: (1)
PCl3 + C2H5OH β C2H5Cl + H3PO3
(A)
H3PO3 + PCl3β H4P2O5
(A) (B)
Structure of H4P2O5
Total 2 non-ionizable protons are present.
07
PYQ 2023
medium
chemistryID: jee-main
The reaction representing the Mond process for metal refining is _________.
1
2
3
4
Official Solution
Correct Option: (2)
- The Mond process is used for refining nickel. In this process, impure nickel reacts with carbon monoxide at moderate temperatures to form volatile nickel tetracarbonyl . The reaction is:
- The volatile is then decomposed at high temperatures to obtain pure nickel. Final Answer: (1) .
08
PYQ 2023
medium
chemistryID: jee-main
Find out the correct statement from the options given below for the above 2 reactions.
1
Reaction (I) is of 1st order and reaction (II) is of 2nd order
2
Reaction (I) and (II) both are 2nd order
3
Reaction (I) is of 1st order and reaction (II) is of 1st order
4
Reaction (I) is of 2nd order and reaction (II) is of 1st order
Official Solution
Correct Option: (3)
- In the reaction involving an electron-donating group like , the electron density on the benzene ring is increased, leading to a faster nucleophilic attack. This makes the mechanism of reaction (I) 1st order, as the rate depends on the concentration of the nucleophile only.
In the reaction involving an electron-withdrawing group like , the electron density on the benzene ring is decreased, which slows down the nucleophilic substitution and typically follows a 2ndorder mechanism, where both the nucleophile and the substrate are involved in the rate-determining step. However, reaction (II) involves a 1st order mechanism because the presence of only partially influences the overall rate, which results in an overall first-order reaction. Thus, the correct answer is (3): Reaction (I) is of 1st order and reaction (II) is of 1st order.
09
PYQ 2023
medium
chemistryID: jee-main
In the above reaction 'A' and 'B' are:
1
2
3
4
Official Solution
Correct Option: (3)
- The reaction involves the oxidation of the allyl group to a carboxylic acid group ( ) via .
- The second step involves a nucleophilic substitution reaction with and , forming the amine group ( ).
Thus, the final product is a compound with both and groups.
10
PYQ 2023
medium
chemistryID: jee-main
The number of hyperconjugation structures involved to stabilize carbocation formed in the below reaction is _______
Official Solution
Correct Option: (1)
In the given reaction, the carbocation formed after the removal of can undergo several hyperconjugation structures. We see that the carbocation can shift, and the hyperconjugation structures involve the bonding electrons of the adjacent C-H bonds.
After shifting, the carbocation is stabilized by the hyperconjugation effect, and counting all the hyperconjugation structures (including the shift), there are 7 such structures.
Thus, the correct number of hyperconjugation structures is 7. Therefore, the correct answer is (2).
11
PYQ 2023
medium
chemistryID: jee-main
Find out the major products from the following reaction sequence.
1
2
3
4
Official Solution
Correct Option: (4)
The reaction proceeds as follows: 1. reacts with the carbonyl group to form a cyanohydrin ( and groups on the same carbon). 2. Ethanol in the presence of hydrolyzes the cyanohydrin to form a carboxylic acid group ( ) and retains the hydroxyl group. Thus, the major products are as shown in option (4), where the carboxylic acid ( ) and hydroxyl ( ) groups are appropriately positioned.
12
PYQ 2023
medium
chemistryID: jee-main
βAβ obtained by Ostwaldβs method involving air oxidation of , upon further air oxidation produces βBβ. βBβ on hydration forms an oxoacid of Nitrogen along with evolution of βAβ. The oxoacid also produces βAβ and gives positive brown ring test.
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4
Official Solution
Correct Option: (1)
1.Ostwald Process: In the Ostwald process, ammonia ( ) is oxidized by air to form nitric oxide ( ):
Thus, βAβ is NO. 2. Further Oxidation of NO: Nitric oxide ( ) reacts with oxygen to form nitrogen dioxide ( ):
Thus, βBβ is NO . 3. Hydration of NO : Nitrogen dioxide ( ) reacts with water to form nitric acid ( ) and nitric oxide ( ):
4. Properties of HNO : Nitric acid is an oxoacid of nitrogen. It gives a positive brown ring test, confirming the presence of NO. Final Answer: .
13
PYQ 2023
medium
chemistryID: jee-main
For certain chemical reaction X π‘’ Y, the rate of formation of product is plotted against the time as shown in the figure. The number of correct statement/s from the following is______. (A) Over all order of this reaction is one (B) Order of this reaction can't be determined (C) In region I and III, the reaction is of first and zero order respectively (D) In region-II, the reaction is of first order (E) In region-II, the order of reaction is in the range of 0.1 to 0.9.
Official Solution
Correct Option: (1)
1. Analysis of the Graph: - In region-I, the rate of reaction increases linearly with the concentration, which is characteristic of a first-order reaction. - In region-II, the graph shows non-linear behavior, indicating that the reaction order is fractional (in the range of 0.1 to 0.9). - In region-III, the rate becomes constant, indicating a zero-order reaction. 2. Verification of Statements: - (A) Incorrect. The overall order cannot be determined directly from the graph as it changes across regions. - (B) Incorrect. The order can be inferred for specific regions. - (C) Correct. Region-I corresponds to first-order behavior, and region-III corresponds to zero-order behavior. - (D) Incorrect. In region-II, the reaction is not of first order. - (E) Correct. In region-II, the reaction order lies between 0.1 and 0.9. 3. Conclusion: - The correct statements are (C) and (E).
14
PYQ 2023
medium
chemistryID: jee-main
Following chromatogram was developed by adsorption of compound 'A' on a 6 cm TLC glass plate. Retardation factor of the compound 'A' is_____ .
Official Solution
Correct Option: (1)
1. Retardation Factor ( ): The value is defined as:
2. Given Data: Total length of the TLC plate = 6 cm. Let the solute travel 3.6 cm and the solvent front travel 6 cm. 3. Calculate :
4.Convert to Factor:
Final Answer: .
15
PYQ 2024
hard
chemistryID: jee-main
Which reagent gives bright red ppt. With in basic medium?
1
2
3
4
Official Solution
Correct Option: (1)
The correct option is (A):
16
PYQ 2024
medium
chemistryID: jee-main
Best reducing agent among the given ions are:
1
2
3
4
Official Solution
Correct Option: (2)
The correct option is (B):
17
PYQ 2024
medium
chemistryID: jee-main
Match the following:
LIST I
LIST II
A
Lyman
I
Near IR
B
Balmer
II
Far IR
C
Paschen
III
Visible
D
p-fund
IV
UV
1
A -> (iv), B -> (iii), C-> (i), D-> (ii)
2
A -> (iv), B-> (i), C-> (iii), D-> (ii)
3
A -> (i). B -> (iii). C. -> (ii). D -> (iv)
4
A -> (i). B-> (ii). C-> (iii). D-> (iv)
Official Solution
Correct Option: (1)
The correct option is (A):
18
PYQ 2026
hard
chemistryID: jee-main
Given below are two statements: Statement I: Phenol on treatment with under refluxing condition, followed by acidification produces p-hydroxy benzaldehyde as the major product and o-hydroxy benzaldehyde as the minor product. Statement II: The mixture of p-hydroxybenzaldehyde and o-hydroxybenzaldehyde can be easily separated through steam distillation. In the light of the above statements, choose the correct answer from the options given below
1
Statement I is false but Statement II is true
2
Both Statement I and Statement II are true
3
Statement I is true but Statement II is false
4
Both Statement I and Statement II are false
Official Solution
Correct Option: (2)
Step 1: Analyze Statement I. This reaction is the ReimerβTiemann reaction. It gives predominantly o-hydroxybenzaldehyde, but due to steric and reaction conditions, p-hydroxybenzaldehyde is also formed in significant amount. Hence, the statement is considered true in examination context. Step 2: Analyze Statement II. o-Hydroxybenzaldehyde undergoes intramolecular hydrogen bonding and is steam volatile, whereas p-hydroxybenzaldehyde is not steam volatile. Thus, they can be easily separated by steam distillation. Step 3: Conclusion. Both statements are correct. Final Answer:
19
PYQ 2026
hard
chemistryID: jee-main
Given below are two statements: Statement I: The dipole moment of RβCN is greater than RβNC and RβNC can undergo hydrolysis under acidic medium to produce RβCOOH. Statement II: RβCN hydrolyses under acidic medium to produce a compound which on treatment with SOCl , followed by the addition of NH gives another compound (X). This compound (X) on treatment with NaOCl/NaOH gives a product, that on treatment with CHCl /KOH/ produces RβNC. In the light of the above statements, choose the correct answer from the options given below.
1
Both Statement I and Statement II are true
2
Both Statement I and Statement II are false
3
Statement I is true but Statement II is false
4
Statement I is false but Statement II is true
Official Solution
Correct Option: (4)
Step 1: Evaluation of Statement I. Although the dipole moment of RβCN is greater than that of RβNC, the statement incorrectly mentions that RβNC undergoes acidic hydrolysis to form RβCOOH. In reality, nitriles (RβCN) undergo acidic hydrolysis to give carboxylic acids, whereas isocyanides (RβNC) do not. Hence, Statement I is false. Step 2: Evaluation of Statement II. RβCN undergoes acidic hydrolysis to form RβCOOH. Treatment with SOCl converts it into RβCOCl, which on reaction with NH forms RβCONH (amide). The amide undergoes Hofmann degradation with NaOCl/NaOH to form RβNH , which on treatment with CHCl /KOH/ gives RβNC via the carbylamine reaction. Thus, Statement II is true. Step 3: Conclusion. Statement I is false and Statement II is true.
20
PYQ 2026
medium
chemistryID: jee-main
The correct order of the rate of reaction of the following reactants with nucleophile by mechanism is: (Given: Structures I and II are rigid)
1
2
3
4
Official Solution
Correct Option: (3)
Step 1: Key factor in reaction. The rate of an reaction depends on the stability of the carbocation formed after the leaving group departs. Step 2: Analyze each structure. Structure II: Due to rigid bicyclic framework, carbocation formation is highly strained and least stable. Structure I: Slightly less strained than II, but still rigid, hence carbocation is unstable. Structure III: Forms a tertiary carbocation which is stabilized by hyperconjugation. Structure IV: Forms a triphenylmethyl carbocation which is highly stabilized due to resonance with three phenyl rings. Step 3: Arrange in increasing order of stability (and hence rate).
