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JEE SECTION - A [CHEMISTY - MCQ]

JEE Main 22-Jan-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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20 questions · 18 auto-graded MCQ + 2 self-marked written.

MCQ 14 Marks
The incorrect statements regarding geometrical isomerism are :
(A) Propene shows geometrical isomerism.
(B) Trans isomer has identical atoms/groups on the opposite sides of the double bond.
(C) Cis-but-2-ene has higher dipole moment than trans-but-2-ene.
(D) 2-methylbut-2-ene shows two geometrical isomers.
(E) Trans-isomer has lower melting point that cis isomer.
Choose the CORRECT answer from the options given below :
  • ✓
    (A), (D) and (E) only
  • B
    (C), (D) and (E) only
  • C
    (B) and (C) only
  • D
    (A) and (E) only
Answer
Correct option: A.
(A), (D) and (E) only
(A) (A), (D) and (E) only
Sol. (A) $CH _3- CH = CH _2$. GI is not possible
(B) Trans isomer has identical atoms/groups on the opposite side of double bond.
(C) Image(dipole moment only)
(D) Image(does not show GI)
(E) Image(Melting point)
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MCQ 24 Marks
From the magnetic behaviour of $\left[ NiCl _4\right]^{2-}$ (paramagnetic) and $\left[ Ni ( CO )_4\right]$ (diamagnetic), choose the correct geometry and oxidation state.
  • A
    $\left[ NiCl _4\right]^{2-}: Ni ^{ II }$, square planar $\left[ Ni ( CO )_4\right]$ : $Ni (0)$, square planar
  • ✓
    $\left[ NiCl _4\right]^{2-}: Ni ^{\prime \prime}$, tetrahedral $\left[ Ni ( CO )_4\right]: Ni (0)$, tetrahedral
  • C
    $\left[ NiCL _4\right]^{2-}: Ni ^{\text {II }}$, tetrahedral $\left[ Ni ( CO )_4\right]$ : $Ni ^{\text {ill }}$, square planar
  • D
    $\left[ NiCl _4\right]^{2-}: Ni (0)$, tetrahedral $\left[ Ni ( CO )_4\right]: Ni (0)$, square planar
Answer
Correct option: B.
$\left[ NiCl _4\right]^{2-}: Ni ^{\prime \prime}$, tetrahedral $\left[ Ni ( CO )_4\right]: Ni (0)$, tetrahedral
(B) $\left[ NiCl _4\right]^{2-}:$ $Ni ^{\prime \prime}$, tetrahedral
$\left[ Ni ( CO )_4\right]: Ni (0)$, tetrahedral
Sol. $\left[ NiCl _4\right]^{2-}$
$Ni ^{+2}-[ Ar ] 3 d^5 4 s^0 \rightarrow sp ^3$, Tetrahedral
Number of unpaired electron $=2$ paramagentic
$\left[ Ni ( CO )_4\right]$,
$Ni (0) \rightarrow[ Ar ] 3 d^{10} 4 s^0$ (After rearrangement)
No unpaired electron
$sp ^3$, Tetrahedral, Diamagnetic
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MCQ 44 Marks
Arrange the following solutions in order of their increasing boiling points.
(i) $10^{-4} M NaCl$
(ii) $10^{-4} M$ Urea
(iii) $10^{-3} M NaCl$
(iv) $10^{-2} M NaCl$
  • ✓
    (ii) < (i) < (iii) < (iv)
  • B
    (ii) < (i) $\cong$ (iii) < (iv)
  • C
    (i) < (ii) < (iii) < (iv)
  • D
    (iv) $<$ (iii) < (i) < (ii)
Answer
Correct option: A.
(ii) < (i) < (iii) < (iv)
(A) (ii) < (i) < (iii) < (iv)
Sol. $\Delta T _{ b }= i K _{ b }, m , \propto i . C$.
where $C =$ concentration
Optionsi.C
(i)$2 \times 10^{-4}$
(ii)$1 \times 10^{-4}$
(iii)$2 \times 10^{-3}$
(iv)$2 \times 10^{-2}$
B.P. order :
(ii) $<$ (i) $<$ (iii) $<$ (iv)
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MCQ 54 Marks
In which of the following complexes the CFSE, $\Delta_0$ will be equal to zero?
  • A
    $\left[ Fe \left( NH _3\right)_6\right] Br _2$
  • B
    $\left[ Fe ( en )_3\right] Cl _3$
  • C
    $K _4\left[ Fe ( CN )_6\right]$
  • ✓
    $K _3\left[ Fe ( SCN )_6\right]$
Answer
Correct option: D.
$K _3\left[ Fe ( SCN )_6\right]$
(D) $K _3\left[ Fe ( SCN )_6\right]$
Sol. For complex $K _3\left[ Fe ( SCN )_6\right]$
Image
Calculation of CFSE
$
\begin{array}{l}
=(-0.4 \times 3+0.6 \times 2) \Delta_0 \\
=0 \Delta_0
\end{array}
$
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MCQ 74 Marks
Which of the following electrolyte can be sued to obtain $H _2 S_2 O _8$ by the process of electrolysis?
  • A
    Dilute solution of sodium sulphate
  • B
    Dilute solution of sulphuric acid
  • ✓
    Concentrated solution of sulphuric acid
  • D
    Acidified dilute solution of sodium sulphate.
Answer
Correct option: C.
Concentrated solution of sulphuric acid
(C) Concentrated solution of sulphuric acid
Sol. Theory based.
At anode
:$
2 HSO_4^{-} \rightarrow H_2 S_2 O_8+2 e^{-}
$
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MCQ 84 Marks
The IUPAC name of the following compound is :
Image
  • A
    2-Carboxy-5-methoxycarbonylhexane.
  • B
    Methyl-6-carboxy-2,5-dimethylhexanoate.
  • C
    Methyl-5-carboxy-2-methylhexanoate.
  • ✓
    6-Methoxycarbonyl-2,5-dimethylhexanoic acid.
Answer
Correct option: D.
6-Methoxycarbonyl-2,5-dimethylhexanoic acid.
(D) 6-Methoxycarbonyl-2,5-dimethylhexanoic acid.
Sol .
Image
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MCQ 94 Marks
A vessel at 1000 K contains $CO _2$ with a pressure of 0.5 atm . Some of $CO _2$ is converted into CO on addition of graphite. If total pressure at equilibrium is 0.8 atm , then $K _{ p }$ is :
  • A
    0.18 atm
  • ✓
    1.8 atm
  • C
    0.3 atm
  • D
    3 atm .
Answer
Correct option: B.
1.8 atm
(B) 1.8 atm
$\begin{array}{ll}\text { Sol. } & CO _2(g)+ C ( s ) \rightleftharpoons 2 CO ( g ) \\ & 0.5 \\ &0.5- x \\ & P _{\text {total }}=0.5+ x =0.8 \\ & x =0.3 \\ & K_{ P }=\frac{(0.6)^2}{0.2}=1.8\end{array}$
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MCQ 104 Marks
Given below are two statements :
Statement I : One mole of propyne reacts with excess of sodium to liberate half a mole of $H _2$ gas.
Statement II : Four g of propyne reacts with $NaNH _2$ to liberate $NH _3$ gas which occupies 224 mL at STP.
In the light of the above statements, choose the most appropriate answer from the options given below:
  • A
    Statement I is correct but Statement II is incorrect.
  • B
    Both Statement I and Statement II are incorrect
  • C
    Statement I is incorrect but Statement II is correct
  • D
    Both Statement I and Statement II are correct.
Answer
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MCQ 114 Marks
Given below are two statements :
Statement I : $CH _3- O - CH _2- Cl$ will undergo $S _{ N } 1$ reaction though it is a primary halide.
Statement II :
Image
will not undergo $S _{ N } 2$ reaction very easily though it is a primary halide.
In the light of the above statements, choose the most appropriate answer from the options given below :
  • A
    Statement I is incorrect but Statement II is correct.
  • B
    Both Statement I and Statement II are incorrect
  • C
    Statement I is correct but Statement II is incorrect
  • ✓
    Both Statement I and Statement II are correct.
Answer
Correct option: D.
Both Statement I and Statement II are correct.
(D) Both Statement I and Statement II are correct.
Sol. $CH _3- O - CH _2- Cl$ will undergo $S _{ N } 1$ mechanism because $CH _3- O -\stackrel{+}{ C } H _2$ is highly stable.

Image
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MCQ 124 Marks
Radius of the first excited state of Helium ion is given as :
$a_0 \rightarrow$ radius of first stationary state of hydrogen atom.
  • A
    $r=\frac{a_0}{2}$
  • B
    $r =\frac{ a _0}{4}$
  • C
    $r=4 a_0$
  • ✓
    $r =2 a _0$
Answer
Correct option: D.
$r =2 a _0$
(D) $r =2 a _0$
Sol. $r=a_0 \frac{ n ^2}{ Z }= a _0 \cdot \frac{(2)^2}{2}=2 a _0$.
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MCQ 134 Marks
A liquid when kept inside a thermally insulated closed vessel at $25^{\circ} C$ was mechanically stirred from outside. What will be the correct option for the following thermodynamic parameters ?
  • ✓
    $\Delta U >0, q =0, w>0$
  • B
    $\Delta U =0, q =0, w =0$
  • C
    $\Delta U <0, q =0, w >0$
  • D
    $\Delta U =0, q <0, w>0$
Answer
Correct option: A.
$\Delta U >0, q =0, w>0$
(A) $\Delta U >0, q =0, w>0$
Sol. Thermally insulated $\Rightarrow q=0$
$
\begin{array}{l}from I ^ 25 \ law\\
\Delta U=q+w \\
\Delta U=w \\
w>0, \Delta U>0
\end{array}
$
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MCQ 144 Marks
Which of the following acids is a vitamin ?
  • A
    Adipic acid
  • B
    Aspartic acid
  • ✓
    Ascorbic acid
  • D
    Saccharic acid
Answer
Correct option: C.
Ascorbic acid
(C) Ascorbic acid
Sol. Vitamin-C is Ascorbic acid.
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MCQ 154 Marks
Match List-I with List-II
List-1List-II
(A)$Al ^{3+}< Mg ^{2+}< Na ^{+}< F ^{-}$(I)Ionisation Enthalpy
(B)B < C < O < N(II)Metallic character
(C)B < Al < Mg < K(III)Electronegativity
(D)Si < P < S < Cl(IV)Ionic radii
Choose the correct answer from the options given below :
  • A
    A-IV, B-I, C-III, D-II
  • B
    A-II, B-III, C-IV, D-I
  • ✓
    A-IV, B-I, C-II, D-III
  • D
    A-III, B-IV, C-II, D-I
Answer
Correct option: C.
A-IV, B-I, C-II, D-III
(C) A-IV, B-I, C-II, D-III
Sol. Ionic radii $- Al ^{3+}< Mg ^{2+}< Na ^{+}< F ^{-}$
Ionisation energy - $B < C < O < N$
Metallic character $- B < Al < Mg < K$
Electron negativity $- Si < P < S < Cl$
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MCQ 164 Marks
Lanthanoid ions with $4 f^7$ configuration are :
(A) $Eu ^{2+}$
(B) $Gd ^{3-}$
(C) $Eu ^{3+}$
(D) $Tb ^{3+}$
(E) $Sm ^{2+}$
Choose the correct answer from the options given below :
  • A
    (A) and (B) only
  • B
    (A) and (D) only
  • C
    (B) and (E) only
  • D
    (B) and (C) only
Answer
(A.) (A) and (B) only
$\begin{array}{ll}\text { Sol. } & { }_{63} Eu ^{2+}-[ Xe ] 4 f ^{\prime} 6 s^{0} \\ & { }_{64} Gd ^{3+}-[ Xe ] 4 f ^7 5 d^0 6 s^{0} \\ & { }_{63} Eu ^{3+}-[ Xe ] 4 f ^6 6 s^{0} \\ & { }_{65} Tb^{3+}-[ Xe ] 4 f ^6 6 s^{0} \\ & { }_{62} Sm ^{2+}-[ Xe ] 4 f ^6 6 s^0 \\ & Eu ^{2+} \& Gd ^{3+}\end{array}$
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MCQ 174 Marks
Which of the following electronegativity order is incorrect?
  • ✓
    $Al < Mg < B < N$
  • B
    $Al < Si < C < N$
  • C
    $Mg < Be < B < N$
  • D
    S $<$ Cl $<$ O $<$ F
Answer
Correct option: A.
$Al < Mg < B < N$
(A) $Al < Mg < B < N$
Image
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MCQ 184 Marks
How many different stereoisomers are possible for the given molecule?

Image
  • A
    3
  • B
    1
  • C
    2
  • ✓
    4
Answer
Correct option: D.
4
(D) 4
Sol.
Image
It has 4 stereoisomers $\left[\begin{array}{ll} R \text { cis } & R \text { trans } \\ S \text { cis } & Strans \end{array}\right]$
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MCQ 194 Marks
Which of the following statement is not true for radioactive decay ?
  • A
    Amount of radioactive substance remained after three half lives is $\frac{1}{8}$ th of original amount.
  • B
    Decay constant does not depend upon temperature.
  • ✓
    Decay constant increases with increase in temperature.
  • D
    Half life is $\ln 2$ times of $\frac{1}{\text { rate constant }}$.
Answer
Correct option: C.
Decay constant increases with increase in temperature.
(C) Decay constant increases with increase in temperature.
Sol. Decay constant is independent of temperature.
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MCQ 204 Marks
A solution of aluminium chloride is electrolysed for 30 minutes using a current of 2 A . The amount of the aluminium deposited at the cathode is ___________ .
[Given : molar mass of aluminium and chlorine are $27 g mol ^{-1}$ and $35.5 g mol ^{-1}$ respectively, Faraday constant $\left.=96500 C mol ^{-1}\right]$.
  • A
    1.660 g
  • B
    1.007 g
  • ✓
    0.336 g
  • D
    0.441 g
Answer
Correct option: C.
0.336 g
(C) 0.336 g
$\begin{array}{l}\text {Sol. gm equivalent of } Al \text { deposited }=\frac{ It }{96500} \\ \begin{array}{l}\frac{ w }{27} \times 3=\frac{2 \times 30 \times 60}{96500} \\ w =0.336 g .\end{array}\end{array}$
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