SECTION - A [CHEMISTY - MCQ] - JEE STD 11 Science Questions

MCQ 14 Marks

Consider the following reactions
$K _2 Cr _2 O _7 \xrightarrow[- H _2 O ]{ KOH }[ A ] \xrightarrow[- H _2 O ]{ H _2 SO _4}[B]+ K _2 SO _4$
The products [A] and [B], respectively are :

A
$K _2 Cr ( OH )_6$ and $Cr _2 O _3$
B
$K _2 CrO _4$ and $Cr _2 O _3$
✓
$K _2 CrO _4$ and $K _2 Cr _2 O _7$
D
$K _2 CrO _4$ and CrO

Answer

Correct option: C.

$K _2 CrO _4$ and $K _2 Cr _2 O _7$

(C)

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MCQ 24 Marks

Given below are two statements about X-ray spectra of elements :
Statement (I) : A plot of $\sqrt{v}(v=$ frequency of X-rays emitted) vs atomic mass is a straight line.
Statement (II) : A plot of $v(v=$ frequency of X-rays emitted) vs atomic number is a straight line. In the light of the above statements choose the correct answer from the options given below :

A
Statement I is true but Statement II is false
B
Both Statement I and Statement II are true
✓
Both Statement I and Statement II are false
D
Statement I is false but Statement II is true

Answer

Correct option: C.

Both Statement I and Statement II are false

(C)

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MCQ 34 Marks

Consider a binary solution of two volatile liquid components 1 and $2 x _1$ and $y _1$ are the mole fractions of component 1 in liquid and vapour phase, respectively. The slope and intercept of the linear plot of $\frac{1}{x_1}$ vs $\frac{1}{y_1}$ are given respectively as :

✓
$\frac{ P _1^0}{ P _2^0}, \frac{ P _2^0- P _1^0}{ P _2^0}$
B
$\frac{ P _2^0}{ P _1^0}, \frac{ P _1^0- P _2^0}{ P _2^0}$
C
$\frac{ P _1^0}{ P _2^0}, \frac{ P _1^0- P _2^0}{ P _2^0}$
D
$\frac{ P _2^0}{ P _1^0}, \frac{ P _2^0- P _1^0}{ P _2^0}$

Answer

Correct option: A.

$\frac{ P _1^0}{ P _2^0}, \frac{ P _2^0- P _1^0}{ P _2^0}$

(A)
$\because$ For liquid solution of two liquids ' 1 ' and ' 2 '
$
\begin{array}{l}
P_1=P_{T y_1}=P_1^{o} x_1 \\
\therefore \frac{P_{T}}{x_1}=\frac{P_1^{o}}{y_1} \\
\therefore \frac{P_2^{o}+x_1\left(P_1^{o}-P_2^{o}\right)}{x_1}=\frac{P_1^{o}}{y_1}
\end{array}
$
$\begin{array}{l}\therefore \frac{ P _2^{ o }}{ x _1}+\left( P _1^{ o }- P _2^{ o }\right)=\frac{ P _1^{ o }}{ y _1} \\ \therefore \frac{1}{ x _1}=\left(\frac{ P _1^{ o }}{ P _2^{ o }}\right)\left(\frac{1}{ y _1}\right)+\left(\frac{ P _2^{ o }- P _1^{ o }}{ P _2^{ o }}\right) \\ \therefore \text { Slope }=\left(\frac{ P _1^{ o }}{ P _2^{ o }}\right) \\ \therefore \text { Intercept }=\left(\frac{ P _2^{ o }- P _1^{ o }}{ P _2^{ o }}\right)\end{array}$

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MCQ 44 Marks

Identify the products $[A]$ and $[B]$, respectively in the following reaction :

Answer

Correct option: C.

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MCQ 54 Marks

pH of water is 7 at $25^{\circ} C$. If water is heated to $80^{\circ} C$, it's pH will :

✓
Decrease
B
Remains the same
C
$H ^{+}$concentration increases, $OH ^{-}$concentration decreases
D
Increase

Answer

Correct option: A.

Decrease

(A)
With increase in temperature, $K _{ w }$ of water increases So, degree of dissociation of water increase $\therefore pH$ as well as pOH of water decrease.

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MCQ 64 Marks

Given below are the atomic numbers of some group 14 elements. The atomic number of the element with lowest melting point is :

A
14
B
6
C
82
✓
50

Answer

Correct option: D.

(D)

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MCQ 74 Marks

Identify the coordination complexes in which the central metal ion has $d ^4$ configuration.
(A) $\left[ FeO _4\right]^{2-}$
(B) $\left[ Mn ( CN )_6\right]^{3-}$
(C) $\left[ Fe ( CN )_6\right]^{3-}$
(D)

(E) $\left[ NiF _6\right]^{2-}$
Choose the correct answer from the options given below :

A
(C) and (E) only
B
(B), (C) and (D) only
✓
(B) and (D) only
D
(A), (B) and (E) only

Answer

Correct option: C.

(B) and (D) only

(C)
$\begin{array}{l} Fe ^{+6}=[ Ar ] 3 d^2 \\ Mn ^{+3}=[ Ar ] 3 d^4 \\ Fe ^{+3}=[ Ar ] 3 d^5 \\ Cr ^{+2}=[ Ar ] 3 d^4 \\ Ni ^{+4}=[ Ar ] 3 d^6\end{array}$

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MCQ 84 Marks

Match list - i with list - ii.

List - I		List - II
(A)	Bronze	(I)	Cu,Ni
(B)	Brass	(II)	Fe,Cr,Ni,C
(C)	UK silver coin	(III)	Cu,Zn
(D)	Stainless Steel	(IV)	Cu,Sn

choose the correct answer from the options given below :

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

Answer

Correct option: B.

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

(B)
Bronze $\rightarrow Cu , Sn$
Brass $\rightarrow Cu , Zn$
UK silver coin $\rightarrow Cu , Ni$
Stainless steel $\rightarrow Fe , Cr , Ni , C$

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MCQ 94 Marks

Which of the following graphs most appropriately represents a zero order reaction?

Answer

Correct option: B.

(B)
For zero order reaction : $A \rightarrow P$
$
\begin{array}{l}
\text { Rate }=k \\
{[A]_t=a_0-k t}
\end{array}
$

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MCQ 104 Marks

Match list - i with list - ii

choose the correct answer from the option given below :

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

Answer

Correct option: B.

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

(B)
ozonlysis product

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MCQ 114 Marks

The ascending order of relative rate of solvolysis of following compounds is

✓
$($ D $)<$ (A) $<$ (B) $<$ (C)
B
$( C )<( B )<( A )<( D )$
C
(D) $<$ (B) $<$ (A) $<$ (C)
D
$( C )<( D )<( B )<( A )$

Answer

Correct option: A.

$($ D $)<$ (A) $<$ (B) $<$ (C)

(A)
Solvolysis or $S _{ N } 1 \propto$ stability of carboccation Stability order

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MCQ 124 Marks

Given below are two statements:Statement (I): For a given shell, the total number of allowed orbitals is given by $n ^2$.
Statement (II) : For any subshell, the spatial orientation of the orbitals is given by $-l$ to $+l$ values including zero.
In the light of the above statements, choose the correct answer from the options given below:

A
Statement I is true but Statement II is false
B
Statement I is false but Statement II is true
✓
Both Statement I and Statement II are true
D
Both Statement I and Statement II are false

Answer

Correct option: C.

Both Statement I and Statement II are true

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MCQ 134 Marks

When a non-volatile solute is added to the solvent, the vapour pressure of the solvent decreases by 10 mm of Hg . The mole fraction of the solute in the solution is 0.2 . What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg ?

✓
0.6
B
0.4
C
0.2
D
0.8

Answer

Correct option: A.

0.6

(A)
$\because P ^{\circ}- P \propto X _{\text {solute }}$
and $\because 10 \propto 0.2$
$
\begin{array}{l}
\therefore 20 \propto 0.4 \\
\begin{aligned}
\therefore X_{\text {solvent }} & =1-X_{\text {solute }} \\
& =1-0.4 \\
\quad= & 0.6
\end{aligned}
\end{array}
$

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MCQ 144 Marks

Given below are two statements:
Statement (I) : The boiling points of alcohols and phenols increase with increase in the number of C -atoms.
Statement (II) : The boiling points of alcohols and phenols are higher in comparison to other class of compounds such as ethers, haloalkanes.
In the light of the above statements, choose the correct answer from the options given below:

A
Both Statement I and Statement II are false
B
Statement I is false but Statement II is true
C
Statement I is true but Statement II is false
✓
Both Statement I and Statement II are true

Answer

Correct option: D.

Both Statement I and Statement II are true

(D)
B.P. $\propto$ M.W.
B.P. $\propto$ Inter molecular hydrogen bondingAlcohol \& Phenol have intermolecular H-bonding

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MCQ 154 Marks

Identify $A , B$ and C in the given below reaction sequence

A
$PbCl _2, PbSO _4, PbCrO _4$
✓
$PbS , PbSO _4, PbCrO _4$
C
$PbS , PbSO _4, Pb\left( CH _3 COO \right)_2$
D
$PbCl _2, Pb\left( SO _4\right)_2, PbCrO _4$

Answer

Correct option: B.

$PbS , PbSO _4, PbCrO _4$

(B)

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MCQ 164 Marks

Consider the reaction
$
X_2 Y(g) \rightleftharpoons X_2(g)+\frac{1}{2} Y_2(g)
$
The equation representing correct relationship between the degree of dissociation ( x ) of $X _2 Y ( g )$ with its equilibrium constant Kp is __________.
Assume $x$ to be very very small.

A
$x=\sqrt[3]{\frac{2 K p}{p}}$
✓
$x=\sqrt[3]{\frac{2 K p^2}{p}}$
C
$x=\sqrt[3]{\frac{K p}{2 p}}$
D
$x=\sqrt[3]{\frac{K p}{p}}$

Answer

Correct option: B.

$x=\sqrt[3]{\frac{2 K p^2}{p}}$

(B)

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MCQ 174 Marks

Given below are two statements:
Consider the following reaction

Statement (I) : In the case of formaldehyde

substituents, hydration is faster.
Statement (II) : In the case of trichloro

due to - I effect of - Cl .
In the light of the above statements, choose the correct answer from the options given below:

A
Statement I true but Statement II is false
✓
Both Statement I and Statement II are true
C
Statement I is false but Statement II is true
D
Both Statement I and Statement II are false

Answer

Correct option: B.

Both Statement I and Statement II are true

(B)
$k _{ eq }=2280$ is for HCHO
$k _{ eq }=2000$ is for chloral
Both data is given in clayden and warren book.
$k _{ eq }>1$ because HCHO and chloral are more electrophilic.

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MCQ 184 Marks

The $\alpha$-Helix and $\beta$ - Pleated sheet structures of protein are associated with its:

A
quaternary structure
B
primary structure
✓
secondary structure
D
tertiary structure

Answer

Correct option: C.

secondary structure

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MCQ 194 Marks

Standard electrode potentials for a few half cells are mentioned below :
$
\begin{array}{l}
E_{Cu^{2+} / Cu}^{o}=0.34 V, E_{Zn^{2+} / Zn}^{o}=-0.76 V \\
E_{Ag^{+} / Ag}^{o}=0.80 V, E_{Mg^{2+} / Mg}^{o}=-2.37 V
\end{array}
$
Which one of the following cells gives the most negative value of $\Delta G ^{ o }$ ?

✓
$Zn \left| Zn ^{2+}(1 M ) \| Ag ^{+}(1 M )\right| Ag$
B
$Zn \left| Zn ^{2+}(1 M )\right|\left| Mg ^{2+}(1 M )\right| Mg$
C
$Ag \left| Ag ^{+}(1 M )\right|\left| Mg ^{2+}(1 M )\right| Mg$
D
$Cu \left| Cu ^{2+}(1 M ) \| Ag ^{+}(1 M )\right| Ag$

Answer

Correct option: A.

$Zn \left| Zn ^{2+}(1 M ) \| Ag ^{+}(1 M )\right| Ag$

(A)
$
\begin{array}{l}
\because \Delta G^{\circ}=-nFE^{\circ} \\
\text { Option (1) } E^{\circ}=0.8+0.76 \\
=1.56 V \\
\therefore \Delta G^{\circ}=-2 \times F \times 1.56 \\
=-3.12 V
\end{array}
$
$
\begin{array}{c}
\text { Option (2) } E^{\circ}=-2.37+0.76 \\
=-1.61 V \\
\therefore \Delta G^{\circ}=-2 \times F \times(-1.61) \\
=+3.22 V
\end{array}
$
$
\begin{array}{c}
\text { Option (3) } \begin{aligned}
E^{\circ} & =-2.37-0.8 \\
& =-3.17 V \\
\therefore \Delta G^{\circ}=-2 & \times F \times(-3.17) \\
& =+6.34
\end{aligned}
\end{array}
$
Option (4)
$
\begin{aligned}
E^{\circ} & =0.8-0.34 \\
& =0.46 V
\end{aligned}
$
$
\begin{aligned}
\Delta G^{\circ} & =-2 \times F \times 0.46 \\
& =-0.92 V
\end{aligned}
$

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MCQ 204 Marks

A
(B) and (D) only
B
(A) and (D) only
✓
(B) and (C) only
D
(A) and (C) only

Answer

Correct option: C.

(B) and (C) only

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