JEE MAIN - Chemistry (2025 - 29th January Morning Shift)
1
1.24 g of AX2 (molar mass 124 g mol−1) is dissolved in 1 kg of water to form a solution with boiling point of 100.015°C, while 25.4 g of AY2 (molar mass 250 g mol−1) in 2 kg of water constitutes a solution with a boiling point of 100.0260°C.
Kb(H2O) = 0.52 kg mol−1
Which of the following is correct?
Answer
(D)
AX2 is fully ionised while AY2 is completely unionised.
2
For a Mg | Mg2+ (aq) || Ag+ (aq) | Ag the correct Nernst Equation is :
Choose the correct answer from the options given below :
Answer
(D)
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
4
The correct increasing order of stability of the complexes based on $\Delta_0$ value is :
I. $[\text{Mn}(\text{CN})_6]^{3-}$
II. $[\text{Co}(\text{CN})_6]^{4-}$
III. $[\text{Fe}(\text{CN})_6]^{4-}$
IV. $[\text{Fe}(\text{CN})_6]^{3-}$
Answer
(A)
I < II < IV < III
5
500 J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are: Given: R = 8.3 J K-1 mol-1
Answer
(B)
348 K and 300 J
6
The molar conductivity of a weak electrolyte when plotted against the square root of its concentration, which of the following is expected to be observed?
Answer
(B)
Molar conductivity decreases sharply with increase in concentration.
7
The correct option with order of melting points of the pairs (Mn, Fe), (Tc, Ru) and (Re, Os) is :
Answer
(D)
Mn < Fe, Tc < Ru and Os < Re
8
The reaction $A_2 + B_2 \rightarrow 2AB$ follows the mechanism:
$A_2 \overset{k_1}{\underset{k_{-1}}{\rightleftharpoons}} A + A$ (fast)
$A + B_2 \xrightarrow{k_2} AB + B$ (slow)
$A + B \rightarrow AB$ (fast)
The overall order of the reaction is:
Answer
(C)
2
9
If $a$0 is denoted as the Bohr radius of hydrogen atom, then what is the de-Broglie wavelength (λ) of the electron present in the second orbit of hydrogen atom? [n : any integer]
Answer
(A)
$\frac{8 \pi a_0}{n}$
10
The standard reduction potential values of some of the p-block ions are given below. Predict the one with the strongest oxidising capacity.
(A) Weight of a substance is the amount of matter present in it.
(B) Mass is the force exerted by gravity on an object.
(C) Volume is the amount of space occupied by a substance.
(D) Temperatures below 0°C are possible in Celsius scale, but in Kelvin scale negative temperature is not possible.
(E) Precision refers to the closeness of various measurements for the same quantity.
Choose the correct answer from the options given below :
Answer
(C)
(C), (D) and (E) Only
12
In the following substitution reaction :
Product 'P' formed is :
Answer
(D)
13
At temperature T, compound $AB_{2(g)}$ dissociates as $AB_{2(g)} \rightleftharpoons AB_{(g)} + \frac{1}{2} B_{2(g)}$ having degree of dissociation $ x $ (small compared to unity). The correct expression for $ x $ in terms of $ K_p $ and $ p $ is:
Answer
(B)
$\sqrt[3]{\frac{2 K_{\mathrm{p}}^2}{\mathrm{p}}}$
14
Match List - I with List - II.
List - I (Complex)
List - II (Hybridisation & Magnetic characters)
(A) [MnBr4]2-
(I) d2sp3 & diamagnetic
(B) [FeF6]3-
(II) sp3d2 & paramagnetic
(C) [Co(C2O4)3]3-
(III) sp3 & diamagnetic
(D) [Ni(CO)4]
(IV) sp3 & paramagnetic
Choose the correct answer from the options given below :
Answer
(C)
(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
15
The product (P) formed in the following reaction is :
Answer
(D)
16
The steam volatile compounds among the following are :
$\text { Choose the correct answer from the options given below : }$
Answer
(C)
(A) and (B) Only
17
Match List - I with List - II.
List - I (Structure)
List - II (IUPAC Name)
(A)
(I) 4-Methylpent-1-ene
(B) (CH3)2C(C3H7)2
(II) 3-Ethyl-5-methylheptane
(C)
(III) 4,4-Dimethylheptane
(D)
(IV) 2-Methyl-1,3-pentadiene
Choose the correct answer from the options given below :
Answer
(A)
(A)-(II), (B)-(III), (C)-(IV), (D)-(I)
18
Total number of nucleophiles from the following is :
Answer
(C)
5
19
An element ‘E’ has the ionisation enthalpy value of 374 kJ mol⁻¹. ‘E’ reacts with elements A, B, C and D with electron gain enthalpy values of −328, −349, −325 and −295 kJ mol⁻¹, respectively. The correct order of the products EA, EB, EC and ED in terms of ionic character is :
Answer
(A)
EB > EA > EC > ED
20
Given below are two statements :
Statement (I) : The radii of isoelectronic species increases in the order.
Mg²⁺ < Na⁺ < F⁻ < O²⁻
Statement (II) : The magnitude of electron gain enthalpy of halogen decreases in the order.
Cl > F > Br > I
In the light of the above statements, choose the most appropriate answer from the options given below :
Answer
(B)
Both Statement I and Statement II are correct
21
The molar mass of the water insoluble product formed from the fusion of chromite ore (FeCr₂O₄) with Na₂CO₃ in presence of O₂ is ___________ g mol⁻¹.
Answer
160
22
Given below are some nitrogen containing compounds :
Each of them is treated with HCl separately. 1.0 g of the most basic compound will consume _______ mg of HCl.
(Given molar mass in g mol−1 C : 12, H : 1, O : 16, Cl : 35.5)
Answer
341
23
If A2B is 30% ionised in an aqueous solution, then the value of van't Hoff factor (i) is _______ × 10−1.
Answer
16
24
0.1 mole of compound ‘S’ will weigh ___________ g.
(Given molar mass in g mol−1 C : 12, H : 1, O : 16)
Answer
13
25
The sum of sigma (σ) and pi (π) bonds in Hex-1,3-dien-5-yne is ________.
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