JEE MAIN - Chemistry (2024 - 4th April Morning Shift)

1
Number of complexes from the following with even number of unpaired "$$\mathrm{d}$$" electrons is ________ $$[\mathrm{V}(\mathrm{H}_2 \mathrm{O})_6]^{3+},[\mathrm{Cr}(\mathrm{H}_2 \mathrm{O})_6]^{2+},[\mathrm{Fe}(\mathrm{H}_2 \mathrm{O})_6]^{3+},[\mathrm{Ni}(\mathrm{H}_2 \mathrm{O})_6]^{3+},[\mathrm{Cu}(\mathrm{H}_2 \mathrm{O})_6]^{2+}$$ [Given atomic numbers: $$\mathrm{V}=23, \mathrm{Cr}=24, \mathrm{Fe}=26, \mathrm{Ni}=28 \mathrm{Cu}=29$$]
Answer
(C)
2
2
What will be the decreasing order of basic strength of the following conjugate bases? $${ }^{-} \mathrm{OH}, \mathrm{R} \overline{\mathrm{O}}, \mathrm{CH}_3 \mathrm{CO} \overline{\mathrm{O}}, \mathrm{Cl}$$
Answer
(D)
$$\mathrm{R} \overline{\mathrm{O}}>{ }^{-} \mathrm{OH}>\mathrm{CH}_3 \mathrm{CO} \overline{\mathrm{O}}>\mathrm{C} \overline{1}$$
3

Given below are two statements :

Statements I : Acidity of $$\alpha$$-hydrogens of aldehydes and ketones is responsible for Aldol reaction.

Statement II : Reaction between benzaldehyde and ethanal will NOT give Cross - Aldol product.

In the light of the above statements, choose the most appropriate answer from the options given below :

Answer
(B)
Statement I is correct but Statement II is incorrect
4

Match List I with List II :

LIST I
Mechanism steps
LIST II
Effect
A. JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Basics of Organic Chemistry Question 36 English 1 I. $$-$$ E effect
B. JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Basics of Organic Chemistry Question 36 English 2 II. $$-$$ R effect
C. JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Basics of Organic Chemistry Question 36 English 3 III. $$+$$ E effect
D. JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Basics of Organic Chemistry Question 36 English 4 IV. $$+$$ R effect

Choose the correct answer from the options given below :

Answer
(D)
(A) - (IV), (B) - (III), (C) - (I), (D) - (II)
5

JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Haloalkanes and Haloarenes Question 20 English

Identify B and C and how are A and C related?

Answer
(A)
JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Haloalkanes and Haloarenes Question 20 English Option 1
6

Identify the correct set of reagents or reaction conditions '$$X$$' and '$$Y$$' in the following set of transformation.

JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Haloalkanes and Haloarenes Question 19 English

Answer
(D)
$$\mathrm{X}=$$ conc.alc. $$\mathrm{NaOH}, 80^{\circ} \mathrm{C}, \mathrm{Y}=\mathrm{HBr} /$$ acetic acid
7
In the precipitation of the iron group (III) in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to :
Answer
(A)
decrease concentration of $${ }^{-} \mathrm{OH}$$ ions
8
The element which shows only one oxidation state other than its elemental form is :
Answer
(D)
Scandium
9
Which of the following is the correct structure of L-Glucose?
Answer
(D)
JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Biomolecules Question 19 English Option 4
10

Identify the product in the following reaction:

JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 25 English

Answer
(A)
JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 25 English Option 1
11

Number of molecules/ions from the following in which the central atom is involved in $$\mathrm{sp}^3$$ hybridization is ________.

$$\mathrm{NO}_3^{-}, \mathrm{BCl}_3, \mathrm{ClO}_2^{-}, \mathrm{ClO}_3^{-}$$

Answer
(A)
2
12
The correct sequence of ligands in the order of decreasing field strength is :
Answer
(B)
$$\mathrm{CO}>\mathrm{H}_2 \mathrm{O}>\mathrm{F}^{-}>\mathrm{S}^{2-}$$
13
The Molarity (M) of an aqueous solution containing $$5.85 \mathrm{~g}$$ of $$\mathrm{NaCl}$$ in $$500 \mathrm{~mL}$$ water is : (Given : Molar Mass $$\mathrm{Na}: 23$$ and $$\mathrm{Cl}: 35.5 \mathrm{~gmol}^{-1}$$)
Answer
(D)
0.2
14
Which among the following is incorrect statement?
Answer
(B)
Hydrogen ion $$(\mathrm{H}^{+})$$ shows negative electromeric effect
15
One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?
Answer
(C)
Metal - Insoluble Salt - Anion electrodes
16

The correct order of first ionization enthalpy values of the following elements is :

(A) O

(B) N

(C) Be

(D) F

(E) B

Choose the correct answer from the options given below :

Answer
(C)
$$\mathrm{E}<\mathrm{C}<\mathrm{A}<\mathrm{B}<\mathrm{D}$$
17
Which of the following nitrogen containing compound does not give Lassaigne's test ?
Answer
(D)
Hydrazine
18
Which one of the following molecules has maximum dipole moment?
Answer
(C)
$$\mathrm{NH}_3$$
19
What pressure (bar) of $$\mathrm{H}_2$$ would be required to make emf of hydrogen electrode zero in pure water at $$25^{\circ} \mathrm{C}$$ ?
Answer
(B)
$$10^{-14}$$
20
Number of elements from the following that CANNOT form compounds with valencies which match with their respective group valencies is ________. B, C, N, S, O, F, P, Al, Si
Answer
(B)
3
21

$$2.5 \mathrm{~g}$$ of a non-volatile, non-electrolyte is dissolved in $$100 \mathrm{~g}$$ of water at $$25^{\circ} \mathrm{C}$$. The solution showed a boiling point elevation by $$2^{\circ} \mathrm{C}$$. Assuming the solute concentration is negligible with respect to the solvent concentration, the vapor pressure of the resulting aqueous solution is _________ $$\mathrm{mm}$$ of $$\mathrm{Hg}$$ (nearest integer)

[Given : Molal boiling point elevation constant of water $\left(\mathrm{K}_{\mathrm{b}}\right)=0.52 \mathrm{~K} . \mathrm{kg} \mathrm{mol}^{-1}$, $$1 \mathrm{~atm}$$ pressure $$=760 \mathrm{~mm}$$ of $$\mathrm{Hg}$$, molar mass of water $$=18 \mathrm{~g} \mathrm{~mol}^{-1}]$$

Answer
707
22
Only $$2 \mathrm{~mL}$$ of $$\mathrm{KMnO}_4$$ solution of unknown molarity is required to reach the end point of a titration of $$20 \mathrm{~mL}$$ of oxalic acid $$(2 \mathrm{M})$$ in acidic medium. The molarity of $$\mathrm{KMnO}_4$$ solution should be ________ M.
Answer
8
23

Consider the following transformation involving first order elementary reaction in each step at constant temperature as shown below.

JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 21 English

Some details of the above reactions are listed below.

Step Rate constant (sec$$^{-1}$$) Activation energy (kJ mol$$^{-1}$$)
1 $$\mathrm{k_1}$$ 300
2 $$\mathrm{k_2}$$ 200
3 $$\mathrm{k_3}$$ $$\mathrm{Ea_3}$$

If the overall rate constant of the above transformation (k) is given as $$\mathrm{k=\frac{k_1 k_2}{k_3}}$$ and the overall activation energy $$(\mathrm{E}_{\mathrm{a}})$$ is $$400 \mathrm{~kJ} \mathrm{~mol} \mathrm{~m}^{-1}$$, then the value of $$\mathrm{Ea}_3$$ is ________ integer)

Answer
100
24
The enthalpy of formation of ethane $$(\mathrm{C}_2 \mathrm{H}_6)$$ from ethylene by addition of hydrogen where the bond-energies of $$\mathrm{C}-\mathrm{H}, \mathrm{C}-\mathrm{C}, \mathrm{C}=\mathrm{C}, \mathrm{H}-\mathrm{H}$$ are $$414 \mathrm{~kJ}, 347 \mathrm{~kJ}, 615 \mathrm{~kJ}$$ and $$435 \mathrm{~kJ}$$ respectively is $$-$$ __________ $$\mathrm{kJ}$$
Answer
125
25
$$\mathrm{Xg}$$ of ethylamine is subjected to reaction with $$\mathrm{NaNO}_2 / \mathrm{HCl}$$ followed by water; evolved dinitrogen gas which occupied $$2.24 \mathrm{~L}$$ volume at STP. X is _________ $$\times 10^{-1} \mathrm{~g}$$.
Answer
45
26

The number of the correct reaction(s) among the following is _______.

JEE Main 2024 (Online) 4th April Morning Shift Chemistry - Compounds Containing Nitrogen Question 26 English

Answer
1
27
The de-Broglie's wavelength of an electron in the $$4^{\text {th }}$$ orbit is ________ $$\pi \mathrm{a}_0$$. ($$\mathrm{a}_0=$$ Bohr's radius)
Answer
8
28
The number of different chain isomers for C$$_7$$H$$_{16}$$ is __________.
Answer
9
29

Number of molecules/species from the following having one unpaired electron is ________.

$$\mathrm{O}_2, \mathrm{O}_2^{-1}, \mathrm{NO}, \mathrm{CN}^{-1}, \mathrm{O}_2^{2-}$$

Answer
2
30

Consider the following reaction

$$\mathrm{MnO}_2+\mathrm{KOH}+\mathrm{O}_2 \rightarrow \mathrm{A}+\mathrm{H}_2 \mathrm{O} \text {. }$$

Product '$$\mathrm{A}$$' in neutral or acidic medium disproportionate to give products '$$\mathrm{B}$$' and '$$\mathrm{C}$$' along with water. The sum of spin-only magnetic moment values of $$\mathrm{B}$$ and $$\mathrm{C}$$ is ________ BM. (nearest integer) (Given atomic number of $$\mathrm{Mn}$$ is 25)

Answer
4