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JEE SECTION - A [CHEMISTY - MCQ]

JEE Main 7-April-2025 Paper - Shift 1 · Gujarat Board (GSEB) STD 11 Science (GSEB - English Medium). 20 questions.

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SECTION - A [CHEMISTY - MCQ]

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MCQ 14 Marks
The reactions which cannot be applied to prepare an alkene by elimination, are
Image
Choose the correct answer from the option given below :
  • A
    B & E Only
  • B
    B, C & D Only
  • C
    A, C & D Only
  • D
    B & D Only
Answer
D. B & D Only
Image
Option (B) and (D) reaction are not able to form alkene as a product.
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MCQ 24 Marks
An octahedral complex having molecular composition $Co.5 \mathrm{NH}_{3}.\mathrm{Cl}. \mathrm{SO}_{4}$ has two isomers A and B. The solution of A gives a white precipitate with $\mathrm{AgNO}_{3}$ solution and the solution of B gives white precipitate with $\mathrm{BaCl}_{2}$ solution. The type of isomerism exhibited by the complex is,
  • A
    Co-ordinate isomerism
  • B
    Linkage isomerism
  • C
    Ionisation isomerism
  • D
    Geometrical isomerism
Answer
C. Ionisation isomerism
(A) complex is $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{SO}_{4}\right)\right] \mathrm{Cl}$
(B) complex is $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}\right] \mathrm{SO}_{4}$
Both (A) and (B) are Ionisation isomers.
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MCQ 34 Marks
Given below are two statements :
Statement I : D-(+)-glucose + D-(+) fructose $\xrightarrow{-\mathrm{H}_{2} \mathrm{O}}$ sucrose
sucrose $\xrightarrow{\text { Hydrolysis }}$ D-(+)-glucose + D-(+) fructose
Statement II : Invert sugar is formed during sucrose hydrolysis.
In the light of the above statements, choose the correct answer from the options given below -
  • A
    Both Statement I and Statement II are true.
  • B
    Statement I is false but Statement II are true.
  • C
    Statement I is true but Statement II is false.
  • D
    Both Statement I and Statement II are false.
Answer
B. Statement I is false but Statement II are true.
On hydrolysis of sucrose gives D-(+)-glucose and D-(-)-fructose while in St. (1) D-(+)-fructose is given evince St-(1) is incorrect.
St. II - It is correct because sucrose on hydrolysis gives invert sugar
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MCQ 44 Marks
A person's wound was exposed to some bacteria and then bacteria growth started to happen at the same place. The wound was later treated with some antibacterial medicine and the rate of bacterial decay (r) was found to be proportional with the square of the existing number of bacteria at any instance. Which of the following set of graphs correctly represents the 'before' and 'after' situation of the application of the medicine?
[Given : $\mathrm{N}=\mathrm{No}$. of bacteria, $\mathrm{t}=$ time, bacterial growth follows I$^{\text {st }}$ order kinetics.]
  • A

    Image
  • B

    Image
  • C

    Image
  • D

    Image
Answer
B.
Image
→ Before applying medicine
$\frac{\mathrm{dA}}{\mathrm{dt}}=\mathrm{K}[\mathrm{A}]$ (First order growth) (Rate law)
$\frac{\mathrm{A}}{\mathrm{A}_{0}}=\frac{\mathrm{N}}{\mathrm{N}_{0}}=\mathrm{e}^{\mathrm{Kt}}$
→ After applying medicine
Active Bacteria $\rightarrow$ Inactive Bacteria
$\quad$$\quad$(A)$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$(I)
$\mathrm{r}=-\frac{\mathrm{dA}}{\mathrm{dt}}=\mathrm{K}[\mathrm{A}]^{2} \quad$ (Rate law)
$y=Kx^{2}$ Parabola
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MCQ 54 Marks
Match the LIST-I with LIST-II.
LIST-I
Molecule/ion		LIST-II
Bond pair : lone pair
(on the central atom)
A.$\mathrm{ICl}_{2}^{-}$I.4 : 2
B.$\mathrm{H}_{2} \mathrm{O}$II.4 : 1
C.$\mathrm{SO}_{2}$III.2 : 3
D.$\mathrm{XeF}_{4}$IV.2 : 2
Choose the correct answer from the options given below :
  • A
    A-IV, B-III, C-II, D-I
  • B
    A-III, B-IV, C-II, D-I
  • C
    A-III, B-IV, C-I, D-II
  • D
    A-II, B-I, C-IV, D-III
Answer
B. A-III, B-IV, C-II, D-I
Image
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MCQ 64 Marks
Which of the following compounds is least likely to give effervescence of $\mathrm{CO}_{2}$ in presence of aq. $\mathrm{NaHCO}_{3}$ ?
  • A

    Image
  • B
    Image
  • C

    $Ph -\stackrel{(+)}{ NH _3} \stackrel{(-)}{ Cl }$
  • D

    Image
Answer
D.
Image
Concept - Those compounds which are more acidic than $\mathrm{H}_{2} \mathrm{CO}_{3}$ can gives effervescence of $\mathrm{CO}_{2}$ with aq. $\mathrm{NaHCO}_{3}$.
Release $\mathrm{CO}_{2} \uparrow$ gas with aq. NaHCO3
$\Rightarrow[\text {A.S.}]_{\text {Comp. }}>[\text {A.S.}]_{\mathrm{H}_{2} \mathrm{CO}_{3}}$
$\rightarrow$ Option 1, 2 and 3 gives effervescence of $\mathrm{CO}_{2}$ gas with $\mathrm{NaHCO}_{3}$
$\rightarrow$ Option (4) Not gives $\mathrm{CO}_{2}$ gas with $\mathrm{NaHCO}_{3}$.
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MCQ 74 Marks
The first transition series metal 'M' has the highest enthalpy of atomisation in its series. One of its aquated ion $\left(\mathrm{M}^{\text {n+}}\right)$ exists in green colour. The nature of the oxide formed by the above $\mathrm{M}^{\mathrm{n}-}$ ion is :
  • A
    neutral
  • B
    acidic
  • C
    basic
  • D
    amphoteric
Answer
C. basic
→ In 3d series Vanadium has highest enthalpy of atomization and colour of $\mathrm{V}^{+3}$ is green.
→ Oxide form by $\mathrm{V}^{+3}$ is $\mathrm{V}_{2} \mathrm{O}_{3}$ (Basic oxide)
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MCQ 84 Marks
The group 14 elements $A$ and $B$ have the first ionisation enthalpy values of 708 and $715 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The above values are lowest among their group members. The nature of their ions $\mathrm{A}^{2+}$ $\mathrm{B}^{4+}$ respectively is
  • A
    both reducing
  • B
    both oxidising
  • C
    reducing and oxidising
  • D
    oxidising and reducing
Answer
C. reducing and oxidising
As per given information of ionisation energy
$A = Sn$ $\&$ $B= Pb$
$\mathrm{A}^{+2}=\mathrm{Sn}^{2+}=$ Reducing agent
$\mathrm{B}^{+4}=\mathrm{Pb}^{+4}=$ Oxidising agent
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MCQ 94 Marks
When a salt is treated with sodium hydroxide solution it gives gas X . On passing gas X through reagent Y a brown coloured precipitate is formed. X and Y respectively, are
  • A
    $\mathrm{X}=\mathrm{NH}_{3}$ and $\mathrm{Y}=\mathrm{HgO}$
  • B
    $\mathrm{X}=\mathrm{NH}_{3}$ and $\mathrm{Y}=\mathrm{K}_{2} \mathrm{HgI}_{4}+\mathrm{KOH}$
  • C
    $\mathrm{X}=\mathrm{NH}_{4} \mathrm{Cl}$ and $\mathrm{Y}=\mathrm{KOH}$
  • D
    $\mathrm{X}=\mathrm{HCl}$ and $\mathrm{Y}=\mathrm{NH}_{4} \mathrm{Cl}$
Answer
B. $\mathrm{X}=\mathrm{NH}_{3}$ and $\mathrm{Y}=\mathrm{K}_{2} \mathrm{HgI}_{4}+\mathrm{KOH}$
$\mathrm{NH}_{4}^{+}+\mathrm{NaOH} \longrightarrow \mathrm{H}_{2} \mathrm{O}+\mathrm{NH}_{3} \uparrow$
Image
$\mathrm{NH}_{3}$ is identify by $\mathrm{K}_{2}\left[\mathrm{HgI}_{4}\right]+\mathrm{KOH}$
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MCQ 104 Marks
The number of valence electrons present in the metal among $\mathrm{Cr}, \mathrm{Co}, \mathrm{Fe}$ and Ni which has the lowest enthalpy of atomisation is
  • A
    8
  • B
    9
  • C
    6
  • D
    10
Answer
C. 6
Out of $\mathrm{Cr}, \mathrm{Co}, \mathrm{Fe}$ and Ni
Chromium has lowest heat of atomisation.
$\mathrm{Cr}=[\mathrm{Ar}] 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{1}$
$\because$ Total six valence $\mathrm{e}^{-}$in Cr.
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MCQ 114 Marks
Given below are two statements :
Statement I : Mohr's salt is composed of only three types of ions-ferrous, ammonium and sulphate.
Statement II : If the molar conductance at infinite dilution of ferrous, ammonium and sulphate ions are $\mathrm{x}_{1}, \mathrm{x}_{2}$ and $\mathrm{x}_{3} \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$, respectively then the molar conductance for Mohr's salt solution at infinite dilution would be given by $\mathrm{x}_{1}+\mathrm{x}_{2}+2 \mathrm{x}_{3}$
In the light of the given statements, choose the correct answer from the options given below :
  • A
    Both statements I and Statement II are false
  • B
    Statement I is false but Statement II is true
  • C
    Statement I is true but Statement II are false
  • D
    Both statements I and Statement II are true
Answer
C. Statement I is true but Statement II are false
Mohr's salt : $\mathrm{FeSO}_{4} \cdot\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} \cdot 6 \mathrm{H}_{2} \mathrm{O}$
Using Kohlrousch law
$\lambda_{\mathrm{m}}^{\infty}($ Mohr's salt $)=\mathrm{x}_{1}+2 \mathrm{x}_{2}+2 \mathrm{x}_{3}$
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MCQ 124 Marks
At the sea level, the dry air mass percentage composition is given as nitrogen gas : 70.0, oxygen gas : 27.0 and argon gas : 3.0. If total pressure is 1.15 atm, then calculate the ratio of followings respectively :
(i) partial pressure of nitrogen gas to partial pressure of oxygen gas
(ii) partial pressure of oxygen gas to partial pressure of argon gas
(Given : Molar mass of N, O and Ar are $14, 16,$ and $40 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively)
  • A
    $4.26,19.3$
  • B
    $2.59,11.85$
  • C
    $5.46,17.8$
  • D
    $2.96,11.2$
Answer
D. $2.96,11.2$
$\frac{\mathrm{P}_{\mathrm{N}_{2}}}{\mathrm{PO}_{2}}=\frac{\mathrm{x}_{\mathrm{N}_{2}} \cdot\mathrm{P}_{\mathrm{T}}}{\mathrm{x}_{\mathrm{O}_{2}} \cdot \mathrm{P}_{\mathrm{T}}}=\frac{\mathrm{n}_{\mathrm{N}_{2}}}{\mathrm{n}_{\mathrm{O}_{2}}}$ {using Dalton's law of partial pressure}
$=\frac{70 / 28}{27 / 32}=2.96$
$\frac{\mathrm{P}_{\mathrm{O}_{2}}}{\mathrm{P}_{\mathrm{Ar}}}=\frac{\mathrm{n}_{\mathrm{O}_{2}}}{\mathrm{n}_{\mathrm{Ar}}}=\frac{27 / 32}{3 / 40}=11.25$
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MCQ 134 Marks
Which of the following is the correct IUPAC name of given organic compound (X) ?
Image
  • A
    2-Bromo-2-methylbut-2-ene
  • B
    3-Bromo-3-methylprop-2-ene
  • C
    1-Bromo-2-methylbut-2-ene
  • D
    4-Bromo-3-methylbut-2-ene
Answer
C. 1-Bromo-2-methylbut-2-ene
Image
1-Bromo-2-methyl but-2-ene
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MCQ 144 Marks

Image
$\quad$$\quad$$\quad$Wavelength $\lambda$ (nanometers)
Which of the following statements are correct, if the threshold frequency of caesium is $5.16 \times 10^{14} \mathrm{~Hz}$ ?
A. When Cs is placed inside a vacuum chamber with an ammeter connected to it and yellow light is focused on Cs the ammeter shows the presence of current.
B. When the brightness of the yellow light is dimmed, the value of the current in the ammeter is reduced.
C. When a red light is used instead to the yellow light, the current produced is higher with respect to the yellow light.
D. When a blue light is used, the ammeter shows the formation of current.
E. When a white light is used, the ammeter shows formation of current.
Choose the correct answer from the options given below :
  • A
    A, D and E Only
  • B
    B, C and D Only
  • C
    A, C, D and E Only
  • D
    A, B, D and E Only
Answer
D. A, B, D and E Only
$\lambda=\frac{C}{v}=\frac{3 \times 10}{5.16 \times 10^{14}}$
$\lambda=581.39 \mathrm{~nm}$
→ $\lambda_{\text {Photon }}$ is near & below yellow light it can show photoelectric effect.
→ If intensity of light decreases photocurrent decreases.
→ Red light will not produce photoelectric effect.
→ $v_{\text {Blue }}>v_{\text {yellow }}$ so photoelectric current will be produced.
→ White light contain all frequencies so it will show photo electric current.
Correct statements are $\mathrm{ABD}$ $\&$ $\mathrm{E}$.
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MCQ 154 Marks
Given below are two statements :
Statement I : Dimethyl ether is completely soluble in water. However, diethyl ether is soluble in water to a very small extent.
Statement II : Sodium metal can be used to dry diethyl ether and not ethyl alcohol.
In the light of given statements, choose the correct answer from the options given below
  • A
    Statement I is false but Statement II are true
  • B
    Both Statement I and Statement II are false
  • C
    Statement I is true but Statement II is false
  • D
    Both Statement I and Statement II are true
Answer
D. Both Statement I and Statement II are true
St-I : - St-I is correct because both given ether are soluble in water $\rightarrow$ Di ethyl ether and butan-1-ol are miscible to almost same extent i.e., 7.5 and 9 gm per 100 ml water due to H -bonding
St-II : - St. II is also correct because sodium metal is not used with ethyl alcohol as $\mathrm{H}_{2}$ gas release with ethyl a below
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MCQ 164 Marks
An aqueous solution of HCl with pH 1.0 is diluted by adding equal volume of water (ignoring dissociation of water). The pH of HCl solution would
(Given $\log 2=0.30$)
  • A
    reduce to 0.5
  • B
    increase to 1.3
  • C
    remain same
  • D
    increase to 2
Answer
B. increase to 1.3
$\mathrm{HCl}_{(\mathrm{aq})} \mathrm{pH}=1 ;\left[\mathrm{H}^{+}\right]=10^{-1}$
If equal volume of water is added concentration will become half
$\left[\mathrm{H}^{+}\right]_{\text {sol }}=\frac{10^{-1}}{2}$
$\mathrm{pH}=1.3$
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MCQ 174 Marks
Total enthalpy change for freezing of 1 mol of water at $10^{\circ} \mathrm{C}$ to ice at $-10^{\circ} \mathrm{C}$ is __________
(Given: $\Delta_{\text {fus }} \mathrm{H}=\mathrm{x} \mathrm{kJ} / \mathrm{mol}$
$\mathrm{C}_{\mathrm{p}}\left[\mathrm{H}_{2} \mathrm{O}(\mathrm{l})\right]=\mathrm{y}$ $\mathrm{J} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$
$\mathrm{C}_{\mathrm{p}}\left[\mathrm{H}_{2} \mathrm{O}(\mathrm{s})\right]=\mathrm{z}$ $\mathrm{J} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$
  • A
    $-x-10 y-10 z$
  • B
    $-10(100 x+y+z)$
  • C
    $10(100 x+y+z)$
  • D
    $x-10 y-10 z$
Answer
B. $-10(100 x+y+z)$
Image
$\Delta \mathrm{H}=1 \times \mathrm{y}(0-10)-\mathrm{x} \times 1000+1 \times \mathrm{z}\left(-10^{\circ}-0^{\circ}\right)$
$\Delta H=-10(100 x+y+z)$ Joule.
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MCQ 184 Marks
Reaction $\mathrm{A}(\mathrm{g}) \rightarrow 2 \mathrm{~B}(\mathrm{~g})+\mathrm{C}(\mathrm{g})$ is a first order reaction. It was started with pure A
$\mathbf{t} / \mathbf{m i n}$Pressure of system at time $\mathbf{t} / \mathbf{m m ~ H g}$
10160
$\infty$240
Which of the following option is incorrect ?
  • A
    Initial pressure of A is 80 mm Hg
  • B
    The reaction never goes to completion
  • C
    Rate constant of the reaction is $1.693 \mathrm{~min}^{-1}$
  • D
    Partial pressure of A after 10 minute is 40 mm Hg
Answer
C. Rate constant of the reaction is $1.693 \mathrm{~min}^{-1}$
$\mathrm{A}(\mathrm{g}) \longrightarrow 2 \mathrm{~B}(\mathrm{~g})+\mathrm{C}(\mathrm{g})$
$\mathrm{t}=0\quad\quad\mathrm{P}_{0}$
$\mathrm{t} \rightarrow \infty \quad 0 \quad\quad 2 \mathrm{P}_{0} \quad\quad \mathrm{P}_{0}$
$\mathrm{P}_{\infty}=3 \mathrm{P}_{0}=240$
$\mathrm{P}_{0}=80 \mathrm{~mm}$ of Hg
$K t=\ln \left(\frac{P_{\infty}-P_{0}}{P_{\infty}-P t}\right)$
$K \times 10=\ln \left(\frac{240-80}{240-160}\right)$
$\mathrm{K}=\frac{\ell \mathrm{n} 2}{10}=0.0693 \mathrm{~min}^{-1}$
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MCQ 204 Marks
Given below are two statements :
Statement I : Ozonolysis followed by treatment with $\mathrm{Zn}, \mathrm{H}_{2} \mathrm{O}$ of cis-2-butene gives ethanal.
Statement II : The production obtained by ozonolysis followed by treatment with $\mathrm{Zn}, \mathrm{H}_{2} \mathrm{O}$ of 3, 6-dimethyloct-4-ene has no chiral carbon atom.
In the light of the above statements, choose the correct answer from the options given below
  • A
    Both Statement I and Statement II are true
  • B
    Statement I is false but Statement II are true
  • C
    Statement I is true but Statement II is false
  • D
    Both Statement I and Statement II are false
Answer
C. Statement I is true but Statement II is false
Image
St-I : Correct statement
St-II : In correct statement because product has chiral centre.
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