JEE MAIN - Chemistry (2025 - 24th January Evening Shift)
1
The successive 5 ionisation energies of an element are $800,2427,3658,25024$ and $32824 \mathrm{~kJ} / \mathrm{mol}$, respectively. By using the above values predict the group in which the above element is present :
Answer
(C)
Group 13
2
Match List - I with List - II.
List - I (Transition metal ion)
List - II (Spin only magnetic moment (B.M.))
(A)
$\mathrm{Ti}^{3+}$
(I)
3.87
(B)
$\mathrm{V}^{2+}$
(II)
0.00
(C)
$\mathrm{Ni}^{2+}$
(III)
1.73
(D)
$\mathrm{Sc}^{3+}$
(IV)
2.84
Choose the correct answer from the options given below :
The heat of formation of $\mathrm{SO}_2(\mathrm{~g})$ is given by :
Answer
(C)
$y-2 x \mathrm{~kcal}$
5
The structure of the major product formed in the following reaction is :
Answer
(B)
6
The elemental composition of a compound is $54.2 \% \mathrm{C}, 9.2 \% \mathrm{H}$ and $36.6 \% \mathrm{O}$.
If the molar mass of the compound is $132 \mathrm{~g} \mathrm{~mol}^{-1}$, the molecular formula of the compound is :
[Given : The relative atomic mass of $\mathrm{C}: \mathrm{H}: \mathrm{O}=12: 1: 16$ ]
Attainment of equilibrium is predicted correctly by :
Answer
(C)
15
Given below are two statements :
Statement (I) : is valid for first order reaction.
Statement (II) : is valid for first order reaction.
In the light of the above statements, choose the correct answer from the options given below :
Answer
(B)
Statement I is true but Statement II is false
16
Given below are two statements :
Statement (I) : Experimentally determined oxygen-oxygen bond lengths in the $\mathrm{O}_3$ are found to be same and the bond length is greater than that of a $\mathrm{O}=\mathrm{O}$ (double bond) but less than that of a single $(\mathrm{O}-\mathrm{O})$ bond.
Statement (II) : The strong lone pair-lone pair repulsion between oxygen atoms is solely responsible for the fact that the bond length in ozone is smaller than that of a double bond $(\mathrm{O}=\mathrm{O})$ but more than that of a single bond $(\mathrm{O}-\mathrm{O})$.
In the light of the above statements, choose the correct answer from the options given below :
Answer
(C)
Statement I is true but Statement II is false
17
Match List - I with List - II.
List - I
List - II
(A)
(I)
Etard reaction
(B)
(II)
Gatterman-Koch reaction
(C)
(III)
Rosenmund reduction
(D)
(IV)
Stephen reaction
Choose the correct answer from the options given below :
Answer
(B)
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
18
When Ethane-1,2-diamine is added progressively to an aqueous solution of Nickel (II) chloride, the sequence of colour change observed will be:
Answer
(C)
Green $\rightarrow$ Pale Blue $\rightarrow$ Blue $\rightarrow$ Violet
19
For hydrogen atom, the orbital/s with lowest energy is/are :
(A) $\mathrm{4 s}$
(B) $3 \mathrm{p}_x$
(C) $3 \mathrm{~d}_{x^2-y^2}$
(D) $3 \mathrm{~d}_{z^2}$
(E) $4 \mathrm{p}_z$
Choose the correct answer from the options given below :
Answer
(C)
(B), (C) and (D) only
20
Identify correct statement/s :
(A) $-\mathrm{OCH}_3$ and $-\mathrm{NHCOCH}_3$ are activating group.
(B) $\quad-\mathrm{CN}$ and -OH are meta directing group.
(C) -CN and $-\mathrm{SO}_3 \mathrm{H}$ are meta directing group.
(D) Activating groups act as ortho - and para directing groups.
(E) Halides are activating groups.
Choose the correct answer from the options given below :
Answer
(A)
$(A),(C)$ and (D) only
21
Consider a complex reaction taking place in three steps with rate constants $\mathrm{k}_1, \mathrm{k}_2$ and $\mathrm{k}_3$ respectively. The overall rate constant $k$ is given by the expression $k=\sqrt{\frac{k_1 k_3}{k_2}}$. If the activation energies of the three steps are 60, 30 and $10 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively, then the overall energy of activation in $\mathrm{kJ} \mathrm{mol}^{-1}$ is _________ . (Nearest integer)
Answer
20
22
The hydrocarbon $(\mathrm{X})$ with molar mass $80 \mathrm{~g} \mathrm{~mol}^{-1}$ and $90 \%$ carbon has _______ degree of unsaturation.
Answer
3
23
In Carius method of estimation of halogen, 0.25 g of an organic compound gave 0.15 g of silver bromide ( AgBr ). The percentage of Bromine in the organic compound is ________ $\times 10^{-1} \%$ (Nearest integer).
(Given : Molar mass of Ag is 108 and Br is $80 \mathrm{~g} \mathrm{~mol}^{-1}$ )
Answer
255
24
The observed and normal molar masses of compound $\mathrm{MX}_2$ are 65.6 and 164 respectively. The percent degree of ionisation of $\mathrm{MX}_2$ is __________%. (Nearest integer)
Answer
75
25
The possible number of stereoisomers for 5-phenylpent-4-en-2-ol is ________.