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JEE Main 2020 (07 Jan Shift 1)

2020 · 75 questions · First 10 Solutions Free
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Q1 mcq
Three point particles of masses $1.0\,kg, \,1.5\, kg$ and $2.5\,kg$ are placed at three corners of a right angle triangle of sides $4.0\,cm, \,3.0\,cm$ and $5.0\,cm$ as shown in the figure. The centre of mass of the system is at a point:
Question 1 image
a.
$0.6\,cm$ right and $2.0\,cm$ above $1\,kg$ mass.
b.
$1.5\,cm$ right and $1.2\,cm$ above $1\,kg$ mass.
c.
$2.0\,cm$ right and $0.9\,cm$ above $1\,kg$ mass.
d.
$0.9\,cm$ right and $2.0\,cm$ above $1\,kg$ mass. Correct Answer

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Q2 mcq
The time period of revolution of electron in its ground state orbit in a hydrogen atom is $1.6 \times 10^{-16}s.$ The frequency of revolution of the electron in its first excited state (in $s^{-1}$ ) is:
a.
$1.6 \times 10^{14}$
b.
$7.8 \times 10^{14}$ Correct Answer
c.
$6.2 \times 10^{15}$
d.
$5.6 \times 10^{12}$

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Q3 mcq
If we need a magnification of $375$ from a compound microscope of tube length $150mm$ and an objective of focal length $5mm,$ the focal length of the eye-piece, should be close to:
a.
$22mm$ Correct Answer
b.
$2mm$
c.
$4mm$
d.
$33mm$

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Q4 mcq
As shown in the figure, a bob of mass $m$ is tied to a massless string whose other end portion is wound on a fly wheel (disc) of radius $r$ and mass $m.$ When released from rest the bob starts falling vertically. When it has covered a distance of $h,$ the angular speed of the wheel will be:
a.
$\frac{1}{r} \sqrt{\frac{4 gh}{3}}$ Correct Answer
b.
$r\sqrt{\frac{3}{2 gh}}$
c.
$\frac{1}{r} \sqrt{\frac{2 gh}{3}}$
d.
$r\sqrt{\frac{3}{4 gh}}$

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Q5 mcq
A parallel plate capacitor has plates of area A separated by distance $d$ between them. It is filled with a dielectric which has a dielectric constant that varies as $K(x) =K_{0}(1 +\alpha x)$ where $x$ is the distance measured from one of the plates. If $(\alpha d) << 1,$ the total capacitance of the system is best given by the expression:
a.
$\frac{AK_{0}\epsilon _{0}}{d}(1 + \frac{\alpha d}{2})$ Correct Answer
b.
$\frac{AK_{0}\epsilon _{0}}{d} [1 +(\frac{\alpha d}{2})^{2}]$
c.
$\frac{AK_{0}\epsilon _{0}}{d}(1 + \frac{\alpha ^{2}d^{2}}{2} )$
d.
$\frac{AK_{0}\epsilon _{0}}{d} (1 +\alpha d)$

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Q6 mcq
Two infinite planes each with uniform surface charge density $+\sigma$ are kept in such a way that the angle between them is $30^{o}$ . The electric field in the region shown between them is given by:
Question 6 image
a.
$\frac{\sigma}{2\in _{0}}[(1 + \sqrt{3})yˆ- \frac{xˆ}{2}]$
b.
$\frac{\sigma}{\in _{0}}[(1 + \frac{\sqrt{3}}{2})yˆ+ \frac{xˆ}{2}]$
c.
$\frac{\sigma}{2\in _{0}}[(1 + \sqrt{3})yˆ+ \frac{xˆ}{2}]$
d.
$\frac{\sigma}{2\in _{0}} [(1 - \frac{\sqrt{3}}{2})yˆ- \frac{xˆ}{2}]$ Correct Answer

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Q7 mcq
If the magnetic field in a plane electromagnetic wave is given by $\vec{B}= 3 \times 10^{-8} sin(1.6 \times 10^{3}x+ 48 \times 10^{10}t)ˆjT,$ then what will be expression for electric field ?
a.
$\vec{E} =(60 sin(1.6 \times 10^{3}x+ 48 \times 10^{10}t)ˆk \frac{V}{m})$
b.
$\vec{E} =(9 sin(1.6 \times 10^{3}x+ 48 \times 10^{10}t)ˆk \frac{V}{m} )$ Correct Answer
c.
$\vec{E} =(3 \times 10^{-8} sin(1.6 \times 10^{3}x+ 48 \times 10^{10}t)ˆj\frac{V}{m}$
d.
$) \vec{E} =(3 \times 10^{-8} sin(1.6 \times 10^{3}x+ 48 \times 10^{10}t)ˆi \frac{V}{m} )$

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Q8 mcq
Consider a circular coil of wire carrying constant current $I,$ forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by $\phi _{i}$ The magnetic flux through the area of the circular coil area is given by $\phi _{0}$ . Which of the following option is correct?
a.
$\phi _{i} =\phi _{0}$
b.
$\phi _{i} >\phi _{0}$
c.
$\phi _{i} <\phi _{0}$
d.
$\phi _{i} = -\phi _{0}$ Correct Answer

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Q9 mcq
Two moles of an ideal gas, with $\frac{C_{P}}{C_{V}} = \frac{5}{3}$ , are mixed with three moles of another ideal gas $\frac{C_{P}}{C_{V}} = \frac{4}{3}$ . The value of $\frac{C_{P}}{C_{V}}$ for the mixture is
a.
$1.45$
b.
$1.50$
c.
$1.47$
d.
$1.42$ Correct Answer

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Q10 mcq
A long solenoid of radius $R$ carries a time $(t)$ dependent current $I(t) =I_{0}t(1 - t)$ . A ring of radius $2R$ is placed coaxially near its middle. During the time interval $0 \leq t\leq 1,$ the induced current $(I_{R})$ and the induced $EMF(V_{R})$ in the ring change as:
a.
Direction of $I_{R}$ remains unchanged and $V_{R}$ is maximum at $t= 0.5$
b.
At $t= 0.25$ direction of $I_{R}$ reverses and $V_{R}$ is maximum
c.
Direction of $I_{R}$ remains unchanged and $V_{R}$ is zero at $t= 0.25$
d.
At $t= 0.5$ direction of $I_{R}$ reverses and $V_{R}$ is zero Correct Answer

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Q11 mcq
Visible light of wavelength $6000 \times 10^{-8}cm$ falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minimum is at $60^{o}$ from the central maximum. If the first minimum is produced at $\theta _{1},$ then $\theta _{1}$ is close to
a.
$20^{o}$
b.
$30^{o}$
c.
$25^{o}$
d.
$45^{o}$
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Q12 mcq
A satellite of mass $M$ is launched vertically upwards with an initial speed $u$ from the surface of the earth. After it reaches height $R$ ( $R=$ radius of the earth), it ejects a rocket of mass $\frac{M}{10}$ so that subsequently the satellite moves in a circular orbit. The kinetic energy of the rocket is ( $G$ is the gravitational constant; $M_{e}$ is the mass of the earth):
a.
$\frac{M}{20}(u^{2}+ \frac{113}{200} \frac{GM_{e}}{R})$
b.
$5M(u^{2} - \frac{119}{200} \frac{GM_{e}}{R})$
c.
$2$ $\frac{3M}{8} (u+\sqrt{\,} \frac{5GM_{e}}{6R})$
d.
$2$ $\frac{M}{20}(u- \sqrt{\,} \frac{2GM_{e}}{3R} )$
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Q13 mcq
The current $I_{1}$ (in $A$ ) flowing through $1\Omega$ resistor in the following circuit is:
Question 13 image
a.
$0.4$
b.
$0.5$
c.
$0.2$
d.
$0.25$
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Q14 nat
A non-isotropic solid metal cube has coefficients of linear expansion as: $5 \times 10^{-5}/^{o}C$ along the x-axis and $5 \times 10^{-6}/^{o}C$ along the y and the z-axis. If the coefficient of volume expansion of the solid is $C \times 10^{-6}/^{o}C$ then the value of $C$ is _____________
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Q15 mcq
A litre of dry air at STP expands adiabatically to a volume of $3$ litres. If $\gamma = 1.40,$ the work done by air is: $(3^{1.4} = 4.6555)$ [Take air to be an ideal gas]
a.
$60.7J$
b.
$90.5J$
c.
$100.8J$
d.
$48J$
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Q16 nat
A loop $ABCDEFA$ of straight edges has six corner points $A(0, 0, 0),B(5, 0, 0),C(5, 5, 0),D(0, 5, 0),E(0, 5, 5)$ and $F(0, 0, 5)$ . The magnetic field in this region is $\vec{B}=(3ˆi+ 4ˆk)T$ . The quantity of flux through the loop $ABCDEFA$ (in $Wb$ ) is _____________
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Q17 mcq
Speed of a transverse wave on a straight wire (mass $6.0\,g,$ length $60\,cm$ and area of cross-section $1.0\,mm^{2}$ is $90\,m\,s^{-1}$ . If the Young's modulus of wire is $16 \times 10^{11}\,N\,m^{-2}$ , the extension of wire over its natural length is:
a.
$0.03\,mm$
b.
$0.02\,mm$
c.
$0.04\,mm$
d.
$0.01\,mm$
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Q18 nat
A Carnot engine operates between two reservoirs of temperatures $900K$ and $300K$ . The engine performs $1200J$ of work per cycle. The heat energy (in $J$ ) delivered by the engine to the low temperature reservoir, in a cycle, is _____________
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Q19 mcq
Which of the following gives a reversible operation?
Question 19 image
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Q20 mcq
A $60HP$ electric motor lifts an elevator having a maximum total load capacity of $2000\,kg.$ If the frictional force on the elevator is $4000\,N,$ the speed of the elevator at full load is close to : $(1\,HP = 746\,W, \,g= 10\,m\,s^{-2})$
a.
$1.7\,m\,s^{-1}$
b.
$1.9\,m\,s^{-1}$
c.
$1.5\,m\,s^{-1}$
d.
$2.0\,m\,s^{-1}$
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Q21 mcq
A polarizer - analyser set is adjusted such that the intensity of light coming out of the analyser is just $36%$ of the original intensity. Assuming that the polarizer - analyser set does not absorb any light, the angle by which the analyser needs to be rotated further, to reduce the output intensity to zero, is $(sin^{-1}(\frac{3}{5} )= 37^{\circ})$
a.
$53^{o}$
b.
$37^{o}$
c.
$90^{o}$
d.
$45^{o}$
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Q22 mcq
A $LCR$ circuit behaves like a clamped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant $'b',$ the correct equivalence would be:
a.
$L\leftrightarrow m,C \leftrightarrow k,R\leftrightarrow b$
b.
$L\leftrightarrow \frac{1}{b} ,C \leftrightarrow \frac{1}{m},R\leftrightarrow \frac{1}{k}$
c.
$L\leftrightarrow k,C \leftrightarrow b,R\leftrightarrow m$
d.
$L\leftrightarrow m,C \leftrightarrow \frac{1}{k} ,R\leftrightarrow b$
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Q23 nat
A particle $(m = 1kg)$ slides down a frictionless track $(AOC)$ starting from rest at a point $A$ (height $2m$ ). After reaching $C,$ the particle continues to move freely in air as a projectile. When it reaching its highest point $P$ (height $1m$ ), the kinetic energy of the particle (in $J$ ) is: (Figure drawn is schematic and not to scale; take $g= 10ms^{-2}$ ) ______________.
Question 23 image
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Q24 mcq
The radius of gyration of a uniform rod of length $l,$ about an axis passing through a point $\frac{l}{4}$ away from the centre of the rod, and perpendicular to it, is:
a.
$\frac{1}{4}$
b.
$\frac{1}{8}$
c.
$\frac{l}{7}$ $\sqrt{\,} _{48} l$
d.
$\frac{l}{3}$ $\sqrt{\,} _{8} l$
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Q25 nat
A beam of electromagnetic radiation of intensity $6.4 \times 10^{-5}W/cm^{2}$ is comprised of wavelength, $\lambda = 310nm$ . It falls normally on a metal (work function $\phi = 2eV$ ) of surface area of $1cm^{2}$ . If one in $10^{3}$ photons ejects an election, total number of electrons ejected in $1s$ is $10^{x}$ . $(hc= 1240eVnm, 1eV = 1.6 \times 10^{-19}J),$ then $x$ is ___________
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Q26 mcq
Oxidation number of potassium in $K_{2}O, K_{2}O_{2}$ and $KO_{2},$ respectively, is:
a.
$+2, + 1$ and $+\frac{1}{2}$
b.
$+1, + 1$ and $+1$
c.
$+1, + 4$ and $+2$
d.
$+1, + 2$ and $+4$
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Q27 mcq
Consider the following reactions: $-(a) (CH_{3})_{3}CCH(OH)CH_{3}^{conc.H_{2}SO}\rightarrow \rightarrow^{4}$ $-(b) (CH_{3})_{2}CHCH(Br)CH_{3}^{alc.KOH}$ $-(c) (CH_{3})_{2}CHCH(Br)CH_{3}^{(CH_{3})_{3}\vec{O}^{\ominus }K}\rightarrow \rightarrow^{\oplus }$ $(d)$ Which of the reaction(s) will not produce Saytzeff product?
Question 27 image
a.
$(a), (c)$ and $(d)$
b.
$(d)$ only
c.
$(c)$ only
d.
$(b)$ and $(d)$
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Q28 nat
Two solutions, $A$ and $B,$ each of $100L$ was made by dissolving $4g$ of $NaOH$ and $9.8g$ of $H_{2}SO_{4}$ in water, respectively. The $pH$ of the resultant solution obtained from mixing $40L$ of solution $A$ and $10L$ of solution $B$ is ____________. $(log \,2 = 0. 3)$
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Q29 mcq
The theory that can completely/properly explain the nature of bonding in $[Ni (CO)_{4}]$ is:
a.
Werner's theory
b.
Molecular orbital theory
c.
Crystal field theory
d.
Valence bond theory
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Q30 nat
During the nuclear explosion, one of the products is $^{90}Sr$ with half life of $6.93$ years. If $1$ $\mu$ $g$ of $^{90}Sr$ was absorbed in the bones of a newly born baby in place of $Ca,$ how much time, in years, is required to reduce it by $90%$ if it is not lost metabolically ____________.
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Q31 mcq
What is the product of following reaction? ?
Question 31 image
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Q32 mcq
The electron gain enthalpy (in $\frac{kJ}{mol}$ ) of fluorine, chlorine, bromine and iodine, respectively, are
a.
$-296, -325, -333$ and $-349$
b.
$-349, -333, -325$ and $-296$
c.
$-333, -349, -325$ and $-296$
d.
$-333, -325, -349$ and $-296$
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Q33 mcq
At $35\,^{o}C,$ the vapour pressure of $CS_{2},$ is $512mm$ Hg and that of acetone is $144\,mmHg.$ A solution of $CS_{2}$ in acetone has a total vapour pressure of $600\,mmHg$ . The false statement amongst the following is:
a.
Raoult's law is not obeyed by this system
b.
a mixture of $100mLCS_{2}$ and $100mL$ acetone has a volume $< 200mL$
c.
$CS_{2}$ and acetone are less attracted to each other than to themselves
d.
heat must be absorbed in order to produce the solution at $35^{o}C$
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Q34 mcq
The IUPAC name of the complex $[Pt(NH_{3})_{2}Cl(NH_{2}CH_{3})]Cl$ is
a.
Diamminechlorido (methanamine) platinum $(II)$ chloride
b.
Diammine(methanamine)chlorido platinum $(II)$ chloride
c.
Diamminechlorido (aminomethane) platinum $(II)$ chloride
d.
Bisammine (methanamine) chlorido platinum $(II)$ chloride
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Q35 mcq
The number of orbitals associated with quantum numbers $n = 5, m_{s} = + \frac{1}{2}$ is:
a.
$11$
b.
$25$
c.
$50$
d.
$15$
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Q36 mcq
Match the following : $(i)$ Riboflavin $(a)$ Beriberi $(ii)$ Thiamine $(b)$ Scurvy $(iii)$ Pyridoxine $(c)$ Cheilosis $(iv)$ Ascorbic acid $(d)$ Convulsions
a.
$(i) -(a), (ii) -(d), (iii) -(c), (iv) -(b)$
b.
$(i) -(c), (ii) -(d), (iii) -(a), (iv) -(b)$
c.
$(i) -(c), (ii) -(a), (iii) -(d), (iv) -(b)$
d.
$(i) -(d), (ii) -(b), (iii) -(a), (iv) -(c)$
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Q37 mcq
The atomic radius of $Ag$ is closest to
a.
$Au$
b.
$Ni$
c.
$Cu$
d.
$Hg$
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Q38 nat
Chlorine reacts with hot and concentrated $NaOH$ and produces compounds $(X)$ and $(Y)$ . Compound $(X)$ gives white precipitate with silver nitrate solution. The average bond order between $Cl$ and $O$ atoms in $(Y)$ is _______________.
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Q39 mcq
Amongst the following statements, that which was not proposed by Dalton was :
a.
chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.
b.
all the atoms of a given element have identical properties including identical mass. Atoms of different elements differ in mass.
c.
when gases combine or reproduced in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same T & P.
d.
matter consists of indivisible atoms.
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Q40 nat
The number of chiral carbons in chloramphenicol is ____________.
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Q41 mcq
The dipole moments of $CCl_{4}, CHCl_{3}$ and $CH_{4}$ are in the order
a.
$CHCl_{3} < CH_{4} = CCl_{4}$
b.
$CCl_{4} < CH_{4} < CHCl_{3}$
c.
$CH_{4} < CCl_{4} < CHCl_{3}$
d.
$CH_{4} = CCl_{4} < CHCl_{3}$
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Q42 mcq
$1$ -methyl ethylene oxide when treated with an excess of $HBr$ produces
Question 42 image
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Q43 mcq
Consider the following reaction: The product $'X'$ is used:
Question 43 image
a.
in protein estimation as an alternative to ninhydrin
b.
in acid base titration as an indicator
c.
as food grade colourant
d.
in laboratory test for phenols
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Q44 mcq
The relative strength of the interionic/ intermolecular forces in a decreasing order is:
a.
dipole-dipole $>$ ion-dipole $>$ ion-ion
b.
ion-dipole $>$ ion-ion $>$ dipole-dipole
c.
ion-dipole $>$ dipole-dipole $>$ ion-ion
d.
ion-ion $>$ ion-dipole $>$ dipole-dipole
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Q45 mcq
The increasing order of $pK_{b}$ for the following compounds will be :
Question 45 image
a.
$(B) < (C) < (A)$
b.
$(A) < (B) < (C)$
c.
$(C) < (A) < (B)$
d.
$(B) < (A) < (C)$
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Q46 mcq
In comparison to the zeolite process for the removal of permanent hardness, the synthetic resin method is
a.
less efficient as it exchanges only anions.
b.
more efficient as it can exchange both cations as well as anions.
c.
less efficient as the resins cannot be regenerated.
d.
more efficient as it can exchange only cations.
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Q47 mcq
Given that the standard potentials $(E^{o})$ of $Cu^{2+} / Cu$ and $Cu^{+} / Cu$ are $0.34V$ and $0.522V$ respectively, the $E^{o}$ of $Cu^{2+} / Cu^{+}$ is:
a.
$0.182V$
b.
$+0.158V$
c.
$-0.182V$
d.
$-0.158V$
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Q48 nat
For the reaction; $A(l) \rightarrow 2B(g)\rightarrow$ $\Delta U = 2.1kcal, \Delta S = 20calK^{-1}$ at $300K.$ Hence $\Delta G$ in $kcal$ is _____________.
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Q49 mcq
The purest form of commercial iron is:
a.
pig iron
b.
wrought iron
c.
cast iron
d.
scrap iron and pig iron
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Q50 mcq
A solution of $m-$ chloroaniline, $m-$ chlorophenol and $m-$ chlorobenzoic acid in ethyl acetate was extracted initially with a saturated solution of $NaHCO_{3}$ to give fraction $A$ . The left over organic phase was extracted with dilute $NaOH$ solution to give fraction $B$ . The final organic layer was labelled as fraction $C$ . Fractions $A, B$ and $C,$ contain respectively:
a.
$m-$ chlorobenzoic acid, $m-$ chloroaniline and $m-$ chlorophenol
b.
$m-$ chlorobenzoic acid, $m-$ chlorophenol and $m-$ chloroaniline
c.
$m-$ chlorophenol, $m-$ chlorobenzoic acid and $m-$ chloroanilinc
d.
$m-$ chloroaniline, $m-$ chlorobenzoic acid and $m-$ chlorophenol
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Q51 mcq
Let $x^{k} +y^{k} =a^{k}, (a,k> 0)$ and $\frac{dy}{dx} +(\frac{y}{x})\frac{1}{3} = 0,$ then $k$ is
a.
$\frac{3}{2}$
b.
$\frac{4}{3}$
c.
$\frac{2}{3}$
d.
$\frac{1}{3}$
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Q52 mcq
Let the function $,f : [-7, 0] \rightarrow \rightarrow R$ be continuous on $[-7, 0]$ and differentiable on $(-7, 0).$ If $f(-7) = -3$ and $f'(x) \leq 2$ for all $x\in (-7, 0),$ then for all such functions $f, \,f(-1) +f(0)$ lies in the interval
a.
$(-\infty , 20]$
b.
$[-3, 11]$
c.
$(-\infty , 11]$
d.
$[-6, 20]$
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Q53 mcq
The area of the region (in sq. units), enclosed by the circle $x^{2} +y^{2} = 2$ which is not common to the region bounded by the parabola $y^{2} =x$ and the straight line $y=x$ , is
a.
$\frac{1}{6}(24\pi -1)$
b.
$\frac{1}{3}(6\pi -1)$
c.
$\frac{1}{3}(12\pi -1)$
d.
$\frac{1}{6}(12\pi -1)$
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Q54 mcq
An unbiased coin is tossed $5$ times. Suppose that a variable $X$ is assigned the value $k$ when $k$ consecutive heads are obtained for $k= 3, 4, 5,$ otherwise $X$ takes the value $-1.$ Then the expected value of $X,$ is
a.
$\frac{3}{16}$
b.
$\frac{1}{8}$
c.
$-\frac{3}{16}$
d.
$- \frac{1}{8}$
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Q55 mcq
If $y(\alpha ) =\sqrt{2}(\frac{tan\alpha +cot\alpha}{1+tan^{2}\alpha})+ \frac{1}{sin^{2}\alpha} , \,\alpha \in (\frac{3\pi}{4},\pi )$ , then $\frac{dy}{d\alpha}$ at $\alpha = \frac{5\pi}{6}$ is
a.
$4$
b.
$\frac{4}{3}$
c.
$-4$
d.
$- \frac{1}{4}$
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Q56 mcq
If $f(a+b+ 1 - x) =f(x),$ for all $x,$ where $a$ and $b$ are fixed positive real numbers, then $b$ $\frac{1}{a+b} \int x(f(x) +f(x+ 1))dx$ is equal to $a$
a.
$b-1$ $\int f(x+ 1)dx$ $a-1$
b.
$b-1$ $\int f(x)dx$ $a-1$
c.
$b+1$ $\int f(x)dx$ $a+1$
d.
$b+1$ $\int f(x+ 1)dx$ $a+1$
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Q57 mcq
If the distance between the foci of an ellipse is $6$ and the distance between its directrix is $12,$ then the length of its latus rectum is
a.
$\sqrt{3}$
b.
$3\sqrt{2}$
c.
$\frac{3}{\sqrt{2}}$
d.
$2\sqrt{3}$
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Q58 nat
$_{x}lim_{\rightarrow 2\rightarrow } \frac{3^{x}+3^{3-}^{x}-12}{3^{-}^{x}2-3^{1-}^{x}}$ is equal to
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Q59 mcq
A vector $\vec{a}=\alpha ˆi+ 2ˆj+\beta ˆk(\alpha ,\beta \in R)$ lies in the plane of the vectors, $\vec{b}= ˆi+ ˆj$ and $\vec{c}= ˆi-ˆj+ 4ˆk.$ If $\vec{a}$ bisects the angle between $\vec{b}$ and $\vec{c},$ then
a.
$\vec{a}\cdot ˆi+ 3 = 0$
b.
$\vec{a}\cdot ˆi+ 1 = 0$
c.
$\vec{a}\cdot ˆk+ 2 = 0$
d.
$\vec{a}\cdot ˆk+ 4 = 0$
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Q60 nat
Let $A(1, 0),B(6, 2)$ and $C(\frac{3}{2}, 6)$ be the vertices of a triangle $ABC.$ If $P$ is a point inside the triangle $ABC$ such that the triangles $APC,APB$ and $BPC$ have equal areas, then the length of the line segment $PQ,$ where $Q$ is the point $(-\frac{7}{6}, - \frac{1}{3} ),$ is
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Q61 mcq
Total number of $6-$ digit numbers in which only and all the five digits $1, 3, 5, 7$ and $9$ appears, is
a.
$\frac{1}{2}(6!)$
b.
$6!$
c.
$5^{6}$
d.
$\frac{5}{2}(6!)$
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Q62 mcq
If $y=y(x)$ is the solution of the differential equation $,e^{y}(\frac{dy}{dx} -1)=e^{x}$ such that $y(0) = 0,$ then $y(1)$ is equal to
a.
$1 + log_{e}2$
b.
$2 + log_{e}2$
c.
$2e$
d.
$log_{e}2$
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Q63 mcq
If $g(x) =x^{2} +x-1$ and $(gof)(x) = 4x^{2} -10x+ 5,$ then $f(\frac{5}{4})$ is equal to
a.
$\frac{3}{2}$
b.
$- \frac{1}{2}$
c.
$\frac{1}{2}$
d.
$- \frac{3}{2}$
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Q64 mcq
For two statements $p$ and $q$ , the logical statement $(p\rightarrow \rightarrow q) \wedge (q\rightarrow ~\rightarrow p)$ is equivalent to
a.
$p$
b.
$q$
c.
$~p$
d.
$~q$
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Q65 nat
Let $S$ be the set of points where the function $,f(x) = |2 -|x-3|,x\in R,$ is not differentiable. Then $\sum _{x\in S}f(f(x))$ is equal to
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Q66 mcq
If the system of linear equations $2x+ 2ay+az= 0$ $2x+ 3by+bz= 0$ $2x+ 4cy+cz= 0,$ where $a,b,c\in R$ are non-zero and distinct; has a non-zero solution, then
a.
$\frac{1}{a}, \frac{1}{b}, \frac{1}{c}$ are in $A.P.$
b.
$a,b,c$ are in $G.P.$
c.
$a+b+c= 0$
d.
$a,b,c$ are in $A.P.$
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Q67 mcq
$1 1 1$ $[ ]$ Let $\alpha$ be a root of the equation $x^{2} +x+ 1 = 0$ and the matrix $A= \frac{1}{\sqrt{3}} 1 \alpha \alpha ^{2} ,$ then the matrix $A^{31}$ is $[_{2}_{4}]$ $1 \alpha \alpha$ equal to
a.
$A^{3}$
b.
$I_{3}$
c.
$A^{2}$
d.
$A$
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Q68 mcq
Let $P$ be a plane passing through the points $(2, 1, 0), (4, 1, 1)$ and $(5, 0, 1)$ and R be any point $(2, 1, 6)$ .Then the image of $R$ in the plane $P$ is
a.
$(6, 5, 2)$
b.
$(6, 5, -2)$
c.
$(4, 3, 2)$
d.
$(3, 4, -2)$
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Q69 mcq
If $Re(\frac{z-1}{2z+i})= 1,$ where $z=x+iy,$ then the point $(x,y)$ lies on a
a.
circle whose centre is at $(-\frac{1}{2}, - \frac{3}{2} )$
b.
straight line whose slope is $-\frac{2}{3}$
c.
straight line whose slope is $\frac{3}{2}$
d.
circle whose diameter is $\frac{\sqrt{5}}{2}$
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Q70 mcq
Five numbers are in $A. P. ,$ whose sum is $25$ and product is $2520.$ If one of these five numbers is $-\frac{1}{2} ,$ then the greatest number amongst them is
a.
$27$
b.
$7$
c.
$\frac{21}{2}$
d.
$16$
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Q71 mcq
Let $\alpha$ and $\beta$ be two real roots of the equation $(k+ 1)tan^{2}x- \sqrt{2}\cdot \lambda tanx= (1 - k),$ where $k(\neq -1)$ and $\lambda$ are real numbers. If $tan^{2}(\alpha +\beta ) = 50,$ then a value of $\lambda$ is
a.
$10\sqrt{2}$
b.
$10$
c.
$5$
d.
$5\sqrt{2}$
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Q72 nat
If the variance of the first $n$ natural numbers is $10$ and the variance of the first $m$ even natural numbers is $16,$ then the value of $m+n$ is equal to
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Q73 nat
If the sum of the coefficients of all even powers of $x$ in the product $(1 +x+x^{2} + … +x^{2n})(1 - x+x^{2} - x^{3} + … +x^{2n})$ is $61,$ then n is equal to
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Q74 mcq
The greatest positive integer $k,$ for which $49^{k} + 1$ is a factor of the sum $49^{125} + 49^{124} + … + 49^{2} + 49 + 1,$ is
a.
$32$
b.
$63$
c.
$60$
d.
$35$
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Q75 mcq
If $y=mx+ 4$ is a tangent to both the parabolas, $y^{2} = 4x$ and $x^{2} = 2by,$ then $b$ is equal to
a.
$-32$
b.
$-64$
c.
$-128$
d.
$128$
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