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JEE Main 2018 (16 Apr Online)

2018 · 90 questions · First 10 Solutions Free
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Q1 mcq
Two particles of the same mass $m$ are moving in circular orbits because of force, given by $F\,(r) = -\frac{16}{r} - r^{3}$ . The first particle is at a distance $r= 1$ , and the second, at $r= 4$ . The best estimate for the ratio of kinetic energies of the first and the second particle is closest to
a.
$3\, \times 10^{-3}$
b.
$6\, \times 10^{2}$
c.
$6\, \times 10^{-2}$ Correct Answer
d.
$10^{-2}$

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Q2 mcq
A charge $q$ is spread uniformly over an insulated loop of radius $r$ . If it is rotated with an angular velocity $\omega$ with respect to normal axis then magnetic moment of the loop is:
a.
$\frac{3}{2} q\omega r^{2}$
b.
$\frac{1}{2} q\omega r^{2}$ Correct Answer
c.
$q\omega r^{2}$
d.
$\frac{4}{3} q\omega r^{2}$

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Q3 mcq
An oscillator of mass $M$ is at rest in its equilibrium position in a potential, $V = \frac{1}{2}k(x\,-X)^{2}$ . A particle of mass $m$ comes from the right with speed $u$ and collides completely inelastic with $M$ and sticks to it. This process repeats every time the oscillator crosses its equilibrium position. The amplitude of oscillations after $13$ collisions is: $(M = 10, \,m= 5, \,u= 1, \,k= 1)$
a.
$\frac{2}{3}$
b.
$\frac{1}{\sqrt{3\,}}$ Correct Answer
c.
$\sqrt{\frac{3}{5}}$
d.
$\frac{1}{2}$

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Q4 mcq
A heating element has a resistance of $100\,\Omega$ at room temperature. When it is connected to a supply of $220\,V$ , a steady current of $2\,A$ passes in it and temperature is $500\,^{o}C$ more than the room temperature. The temperature coefficient of resistance of the heating element is
a.
$5\, \times 10^{-4}^{o}C^{-1}$
b.
$2\, \times 10^{-4}^{o}C^{-1}$ Correct Answer
c.
$1\, \times 10^{-4}^{o}C^{-1}$
d.
$0.5\, \times 10^{-4}^{o}C^{-1}$

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Q5 mcq
Unpolarized light of intensity $I$ is incident on a system of two polarizers, $A$ followed by $B$ . The intensity of emergent light is $\frac{I}{2}$ . If a third the polarizer $C$ is placed between $A$ and $B$ the intensity of emergent light is reduced to $\frac{I}{3}$ . The angle between the polarizers $A$ and $C$ is $\theta$ , then
a.
$cos\theta =( \frac{2}{3})\frac{1}{4}$ Correct Answer
b.
$cos\theta =(\frac{1}{3})\frac{1}{4}$
c.
$cos\theta =( \frac{1}{3})\frac{1}{2}$
d.
$cos\theta =(\frac{2}{3})\frac{1}{2}$

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Q6 mcq
A plane electromagnetic wave of wavelength $\lambda$ has an intensity $I$ . It is propagating along the positive $Y-$ direction. The allowed expressions for the electric and magnetic fields are given by:
a.
$\vec{E} = \,\sqrt{\,} \frac{2\,I}{\epsilon _{0}c}\, cos[\frac{2\pi}{\lambda}(y- ct)]ˆk$ , $\vec{B}= + \frac{1}{c}Eˆi$ Correct Answer
b.
$\vec{E} = \,\sqrt{\,} \frac{I}{\epsilon _{0}c}\, cos[ \frac{2\pi}{\lambda}(y- ct)]ˆk$ , $\vec{B}= +\frac{1}{c} Eˆi$
c.
$\vec{E} = \,\sqrt{\,} \frac{2\,I}{\epsilon _{0}c}\, cos[\frac{2\pi}{\lambda}(y+ct)]ˆk$ , $\vec{B}= + \frac{1}{c}Eˆi$
d.
$\vec{E} = \,\sqrt{\,} \frac{I}{\epsilon _{0}c}\, cos[ \frac{2\pi}{\lambda}(y- ct)]ˆi$ , $\vec{B}= +\frac{1}{c} Eˆk$

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Q7 mcq
A galvanometer with its coil resistance $25\,\Omega$ requires a current of $1\, mA$ for its full deflection. In order to construct an ammeter to read up to a current of $2\,A$ the approximate value of the shunt resistance should be:
a.
$1.25\, \times 10^{-2\,}\Omega$ Correct Answer
b.
$2.5\, \times 10^{-3\,}\Omega$
c.
$2.5\, \times 10^{-2\,}\Omega$
d.
$1.25\, \times 10^{-3\,}\Omega$

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Q8 mcq
The relative uncertainty in the period of a satellite orbiting around the earth is $10^{-2}$ . If the relative uncertainty in the radius of the orbit is negligible, the relative uncertainty in the mass of the earth is:
a.
$2\, \times \,10^{-2}$ Correct Answer
b.
$6\, \times \,10^{-2}$
c.
$3\, \times \,10^{-2}$
d.
$10^{-2}$

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Q9 mcq
The de-Broglie wavelength $(\lambda _{B})$ associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state $(\lambda _{G})$ by:
a.
$\lambda _{B} = \,3\lambda _{G}$ Correct Answer
b.
$\lambda _{B} = 2\lambda _{G}$
c.
$\lambda _{B} =\lambda \frac{G}{3}$
d.
$\lambda _{B} =\lambda \frac{G}{2}$

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Q10 mcq
In the following circuit the switch $S$ is closed at $t\, = 0$ . The charge on the capacitor $C_{1}$ as a function of time will be given by $(C_{eq} = \, \frac{C_{1}C_{2}}{C_{1}+\,C_{2}})$
Question 10 image
a.
$C_{1}E [1 -exp(- \frac{tR}{C_{1}})]$
b.
$C_{eq}E\,exp[-\frac{t}{RC_{eq}}]$
c.
$C_{eq}E [1 -exp(-\frac{t}{RC_{eq}})]$ Correct Answer
d.
$C_{2}E [1 -exp(-\frac{t}{RC_{2}})]$

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Q11 mcq
Two moles of helium are mixed with n moles of hydrogen. If $\frac{C_{p}}{C_{v}} = \frac{3}{2}$ for the mixture then the value of $n$ is,
a.
1
b.
3
c.
2
d.
$\frac{3}{2}$
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Q12 mcq
A particle executes simple harmonic motion and it is located at $x=a, \,b$ and $c$ at time $t_{0}, \,2t_{0}\,and\,3t_{0}$ respectively. The frequency of the oscillation is:
a.
$\frac{1}{2\pi t_{0}}cos^{-1}( \frac{a+c}{2b})$
b.
$\frac{1}{2\pi t_{0}} cos^{-1}(\frac{a+2b}{3c})$
c.
$\frac{1}{2\pi t_{0}}cos^{-1}( \frac{a+b}{2c})$
d.
$\frac{1}{2\pi t_{0}}cos^{-1}(\frac{2a+3c}{b})$
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Q13 mcq
Suppose that the angular velocity of rotation of the Earth is increased. Then, as a consequence,
a.
weight of the object, everywhere on the earth, will decrease.
b.
weight of the object, everywhere on the earth, will increase.
c.
except at poles, weight of the object on the earth, will decrease.
d.
there will be no change in weight anywhere on the earth.
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Q14 mcq
At some instant, a radioactive sample $S_{1}$ having an activity $5\mu Ci$ has twice the number of nuclei as another sample $S_{2}$ which has an activity of $10\mu Ci$ . The half lives of $S_{1}$ and $S_{2}$ are :
a.
$4 : 1$
b.
$1 : 4$
c.
$1 : 2$
d.
$2 : 1$
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Q15 mcq
The end correction of a resonance column is $1\, cm$ . If the shortest length resonating with the tuning fork is $10\, cm$ , the next resonating length should be
a.
$32\, cm$
b.
$40\, cm$
c.
$28\, cm$
d.
$36\, cm$
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Q16 mcq
Both the nucleus and the atom of some element are in their respective first excited states. They get de-excited by emitting photons of wavelengths $\lambda _{N}, \,\lambda _{A}$ respectively. The ratio $\frac{\lambda _{N}}{\lambda _{A}}$ is closest to:
a.
$10^{-1}$
b.
$10^{-6}$
c.
$10$
d.
$10^{-10}$
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Q17 mcq
A body of mass $m$ starts moving from rest along $x-$ axis so that its velocity varies as $v=a\sqrt{s}$ where $a$ is a constant and $s$ is the distance covered by the body. The total work done by all the forces acting on the body in the first $t$ second after the start of the motion is
a.
$8\,ma^{4}t^{2}$
b.
$\frac{1}{4} ma^{4}t^{2}$
c.
$4\,ma^{4}t^{2}$
d.
$\frac{1}{8}ma^{4}t^{2}$
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Q18 mcq
In a circuit for finding the resistance of a galvanometer by half deflection method, a $6\,V$ battery and a high resistance of $11\,k\Omega$ are used. The figure of merit of the galvanometer is $60\,$ $\mu$ $A\, division^{-1}$ . In the absence of shunt resistance, the galvanometer produces a deflection of $\theta = 9$ divisions when current flows in the circuit. The value of the shunt resistance that can cause the deflection of $\frac{\theta}{2}$ , is closest to:
a.
$550\,\Omega$
b.
$220\,\Omega$
c.
$55\,\Omega$
d.
$110\,\Omega$
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Q19 mcq
Two sitar strings, $A$ and $B$ playing the note ' $Dha$ ' are slightly out of tune and produce beats of frequency $5\, Hz$ . The tension of the string $B$ is slightly increased and the beat frequency is found to decrease by $3\, Hz$ . If the frequency of $A$ is $425\, Hz$ . The original frequency of $B$ is
a.
$428\, Hz$
b.
$430\, Hz$
c.
$422\, Hz$
d.
$420\, Hz$
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Q20 mcq
A ray of light is incident at an angle of $60^{\circ }$ on one face of a prism of angle $30^{\circ }$ . The emergent ray of light makes an angle of $30^{\circ }$ with incident ray. The angle made by the emergent ray with second face of prism will be:
a.
$0^{\circ}$
b.
$90^{\circ}$
c.
$30^{\circ}$
d.
$45^{\circ}$
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Q21 mcq
The percentage errors in quantities $P$ , $Q$ , $R$ and $S$ are $0. 5%$ , $1%$ , $3%$ and $1. 5%$ respectively in the measurement of a physical quantity $A= \frac{P^{3}Q^{2}}{\sqrt{R}S}$ . The maximum percentage error in the value of $A$ will be:
a.
$6.5\,%$
b.
$7.5\,%$
c.
$6.0\,%$
d.
$\,8.5\,%$
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Q22 mcq
A coil of cross-sectional area $A$ having $n$ turns is placed in a uniform magnetic field $B$ . When it is rotated with an angular velocity $\omega$ $,$ the maximum e.m.f. induced in the coil will be:
a.
$\frac{3}{2}nBA\omega$
b.
$3nBA\omega$
c.
$nBA\omega$
d.
$\frac{1}{2}nBA\omega$
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Q23 mcq
One mole of an ideal monatomic gas is taken along the path $ABCA$ as shown in the $PV$ diagram. The maximum temperature attained by the gas along the path $BC$ is given by:
Question 23 image
a.
$\frac{25}{4} \frac{P_{0}V_{0}}{R}$
b.
$\frac{5}{8} \frac{P_{0}V_{0}}{R}$
c.
$\frac{25}{8} \frac{P_{0}V_{0}}{R}$
d.
$\frac{25}{16} \frac{P_{0}V_{0}}{R}$
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Q24 mcq
In the given circuit the current through zener diode is:
Question 24 image
a.
$3. 3\, mA$
b.
$2. 5\, mA$
c.
$5. 5\, mA$
d.
$6. 7\, mA$
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Q25 mcq
A power transmission line feeds input power at $\,2300\,V$ to a step-down transformer with its primary windings having $4000\,$ turns giving the output power at $230\,V$ . If the current in the primary coil of the transformer is $5\,A$ and its efficiency is $90\,%$ , the output current would be:
a.
$45\,A$
b.
$50\,A$
c.
$20\,A$
d.
$25\,A$
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Q26 mcq
A carrier wave of peak voltage $14\,V$ is used for transmitting a message signal. The peak voltage of the modulating signal given to achieve a modulation index of $80%$ will be:
a.
$22 .4 \,V$
b.
$7\,V$
c.
$11 .2 \,V$
d.
$28\,V$
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Q27 mcq
Let $\vec{A}= ˆi\, + \,ˆj \,and\,\vec{B}= 2ˆi-\,ˆj$ . The magnitude of a coplanar vector $\vec{C}$ such that $( ) ( )$ $\vec{A}\,. \,\vec{C} \vec{B}. \,\vec{C} = \,\vec{A}\,. \,\vec{B}$ is given by:
a.
$\frac{=}{9}$ $\sqrt{\,}$
b.
$\sqrt{\frac{20}{9}}$
c.
$\frac{12}{5}$ $\sqrt{\,} _{9}$
d.
$\sqrt{\frac{10}{9}}$
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Q28 mcq
Two identical conducting spheres $A$ and $B$ carry an equal charges. They are separated by a distance much larger than their diameters, and the force between them is $F$ . A third identical conducting sphere, $C$ , is uncharged. Sphere $C$ is first touched to $A$ , then to $B$ , and then removed. As a result, the force between $A$ and $B$ would be equal to:
a.
$\frac{3F}{4}$
b.
$\frac{F}{2}$
c.
$\frac{3F}{8}$
d.
$F$
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Q29 mcq
A small soap bubble of radius 4cm is trapped inside another bubble of radius 6cm without any contact. Let $P_{2}$ be the pressure inside the inner bubble and $P_{0}$ , the pressure outside the outer bubble. Radius of another bubble with pressure difference $P_{2}- P_{0}$ between its inside and outside would be:
a.
$2 .4 \, cm$
b.
$12\, cm$
c.
$4 .8 \, cm$
d.
$6\, cm$
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Q30 mcq
A thin circular disk is in the $xy$ plane as shown in the figure. The ratio of its moment of inertia about $z$ and $z'$ axes will be:
Question 30 image
a.
$1\, : 4$
b.
$1 : 5$
c.
$1 : 3$
d.
$1 : 2$
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Q31 mcq
When $XO_{2}$ is fused with an alkali metal hydroxide in presence of an oxidizing agent such as $KNO_{3}$ ; a dark green product is formed which disproportionate in acidic solution to afford a dark purple solution. $X$ is:
a.
$Mn$
b.
$Cr$
c.
$V$
d.
$Ti$
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Q32 mcq
Assuming ideal gas behavior, the ratio of density of ammonia to that of hydrogen chloride at same temperature and pressure is: (Atomic weight of Cl is 35.5 u)
a.
$1.46$
b.
$1.64$
c.
$0.46$
d.
$0.64$
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Q33 mcq
Which of the following compounds will most readily be dehydrated to give alkene under acidic condition?
a.
4 - Hydroxypentan - 2-one
b.
3- Hydroxypentan-2-one
c.
1-Pentanol
d.
2-Hydroxycyclopentanone
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Q34 mcq
Which of the following conversions involves change in both shape and hybridisation?
a.
$H_{2}O\, \rightarrow \,\rightarrow H_{3}O^{+}$
b.
$BF_{3}\, \rightarrow \rightarrow BF_{4}^{-}$
c.
$CH_{4}\, \rightarrow \,\rightarrow C_{2}H_{6}$
d.
$NH_{3}\, \rightarrow \,\rightarrow NH^{+}_{4}$
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Q35 mcq
When 9.65 ampere current was passed for 1.0 hour into nitrobenzene in acidic medium, the amount of p- aminophenol produced is:
a.
109.0 g
b.
98.1 g
c.
9.81 g
d.
10.9 g
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Q36 mcq
In a complexometric titration of metal ion with ligand $M\,(Metal\,ion) +L(Ligand) \rightarrow \rightarrow C\,(Complex)$ end point is estimated spectrophotometrically (through light absorption). If 'M' and 'C' do not absorb light and only 'L' absorbs then the titration plot between absorbed light $(A)$ versus volume of ligand 'L' $(V)$ would look like:
Question 36 image
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Q37 mcq
For standardizing $\vec{N}aOH$ solution, which of the following is used as a primary standard?
a.
Sodium tetra borate
b.
Ferrous Ammonium sulphate
c.
Oxalic acid
d.
Dil. HCl
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Q38 mcq
The mass of a non-volatile, non-electrolyte solute (molar mass $= \,50\,g\, mol^{-1}$ ) needed to be dissolved in 114 g octane to reduce its vapour pressure by 75 %, is:
a.
$37.5\,g$
b.
$75\,g$
c.
$150\,g$
d.
$50\,g$
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Q39 mcq
At 320 K, a gas $A_{2}$ is 20 % dissociated to $A(g)$ . The standard Gibbs free energy change at $320\,K\,and\,1\,atm\,in\,J mol^{-1}$ is approximately: $(R\, = \,8 .314 \, JK^{-1} \, mol^{-1} \,; ln 2\, = \,0 .693 \,; ln 3\, = \,1 .098)$
a.
1844
b.
2068
c.
4281
d.
4763
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Q40 mcq
Theincorrect statement is:
a.
$Cu^{2+}$ ion gives chocolate coloured precipitate with potassium ferrocyanide solution
b.
$Cu^{2+} \, and \, Ni^{2+}$ ions give black precipitate with $H_{2}S$ in presence of HCl solution
c.
Ferric ion gives blood red colour with potassium thiocyanate
d.
$Cu^{2+}$ salts give red coloured borax bead test in reducing flame
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Q41 mcq
The major product B formed in the following reaction sequence is:
Question 41 image
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Q42 mcq
Which of the following complexes will show geometrical isomerism?
a.
Potassium tris(oxalato)chromate(III)
b.
Pentaaquachlorochromium(II)chloride
c.
Aquachlorobis(ethylenediamine)cobalt(II)chloride
d.
Potassiumamminetrichloroplatinate(II)
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Q43 mcq
Among the following, the incorrect statement is
a.
cellulose and amylose has $1, 4-$ glycosidic linkage.
b.
lactose contains $\beta$ $-D-$ galactose and $\beta$ $-D-$ glucose.
c.
maltose and lactose has $1, 4-$ glycosidic linkage.
d.
sucrose and amylose has $1, 2-$ glycosidic linkage.
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Q44 mcq
The major product of the following reaction is:
Question 44 image
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Q45 mcq
Among the oxides of nitrogen: $N_{2}O_{3}, \,N_{2}O_{4}\,and\,N_{2}O_{5};$ the molecule $(s)$ having nitrogen - nitrogen bond is/are:
a.
$N_{2}O_{3}\,and\,N_{2}O_{4}$
b.
$N_{2}O_{4}\,and\,N_{2}O_{5}$
c.
$N_{2}O_{3}\,and\,N_{2}O_{5}$
d.
$\,Only\,N_{2}O_{5}$
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Q46 mcq
The major product of the following reaction is:
Question 46 image
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Q47 mcq
A group 13 element $'X'$ reacts with chlorine gas to produce a compound $XCl_{3}. \, XCl_{3}$ is electron deficient and easily reacts with $NH_{3}\, to \, form \, Cl_{3}X ←NH_{3}$ adduct; however, $XCl_{3}$ does not dimerize. X is:
a.
B
b.
Al
c.
In
d.
Ga
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Q48 mcq
For which of the following processes, $\Delta S$ is negative?
a.
$C\,(diamond) C\,(graphite)$
b.
$N_{2}(g, 1 atm) N_{2}(g, \,5\, atm)$
c.
$N_{2}(g, \,273K) \rightarrow N\rightarrow_{2}(g, \,300K)$
d.
$H_{2}(g) \rightarrow 2H(\rightarrow \vec{g})$
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Q49 mcq
In the extraction of copper from its sulphide ore, metal is finally obtained by the oxidation of cuprous sulphide with:
a.
$SO_{2}$
b.
$Fe_{2}O_{3}$
c.
$Cu_{2}O$
d.
$CO$
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Q50 mcq
Products A and B formed in the following reactions are respectively:
Question 50 image
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Q51 mcq
The gas phase reaction $2 NO_{2}(g)\, \,N_{2}O_{4}\,(g)$ is an exothermic reaction. The decomposition of $N_{2}O_{4}$ , in equilibrium mixture of $NO_{2}\,(g)\, a\vec{n}d \,N_{2}O_{4}\,(g)$ can be increased by:
a.
Addition of an inert gas at constant pressure
b.
Lowering the temperature
c.
Increasing the pressure
d.
Addition of an inert gas at constant volume
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Q52 mcq
The correct match between items of List-I and List-II is: List -I List - II (A) Phenelzine (P) Pyrimidine (B) Chloroxylenol (Q) Furan (C) Uracil (R) Hydrazine (D) Ranitidine (S) Phenol
a.
$(A) -(S), \,(B) -(R), \,(C) -(Q), \,(D) -(P)$
b.
$(A) -(R), \,(B) -(S), \,(C) -(P), \,(D) -(Q)$
c.
$(A) -(R), \,(B) -(S), \,(C) -(Q), \,(D) -(P)$
d.
$(A) -(S), \,(B) -(R), \,(C) -(P), \,(D) -(Q)$
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Q53 mcq
The most polar compound among the following is:
Question 53 image
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Q54 mcq
In Wilkinson's catalyst, the hybridization of central metal ion and its shape are respectively:
a.
$sp^{3}d$ , trigonal bipyramidal
b.
$d^{2}sp^{3}$ , octahedral
c.
$dsp^{2}$ , square planar
d.
$sp^{3}$ , tetrahedral
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Q55 mcq
An unknown chlorohydrocarbon has 3.55 % of chlorine. If each molecule of the hydrocarbon has one chlorine atom only; chlorine atoms present in 1 g of chlorohydrocarbon are :(Atomic wt. of $Cl = 35 .5 \,u;$ Avogadro constant $= 6 .023 \times 10^{23}\, mol^{-1}$ )
a.
$6.023\, \times 10^{9}$
b.
$6.023\, \times 10^{23}$
c.
$6.023\, \times 10^{21}$
d.
$6.023\, \times 10^{20}$
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Q56 mcq
The major product of the following reaction is:
Question 56 image
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Q57 mcq
If 50 % of a reaction occurs in 100 second and 75 % of the reaction occurs in 200 second, the order of this reaction is:
a.
2
b.
3
c.
Zero
d.
1
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Q58 mcq
Which one of the following is not a property of physical adsorption?
a.
Higher the pressure, more the adsorption
b.
Greater the surface area, more the adsorption
c.
Lower the temperature, more the adsorption
d.
Unilayer adsorption occurs
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Q59 mcq
Which of the following statements is false?
a.
Splitting of spectral lines in electrical field is called Stark effect
b.
Frequency of emitted radiation from a black body goes from a higher wavelength to lower wavelength as the temperature increases
c.
Photon has momentum as well as wavelength
d.
Rydberg constant has unit of energy
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Q60 mcq
The incorrect geometry is represented by:
a.
$NF_{3}$ - trigonal planar
b.
$BF_{3}$ - trigonal planar
c.
$AsF_{5}$ - trigonal bipyramidal
d.
$H_{2}O$ - bent
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Q61 mcq
If the angle between the lines $\frac{x}{2} = \frac{y}{2} = \frac{z}{1}$ and $\frac{5-x}{-2} = \frac{7y-14}{P} = \frac{z-3}{4}$ is $cos^{-1}(\frac{2}{3}),$ then $P$ is equal to
a.
$\frac{2}{7}$
b.
$\frac{7}{2}$
c.
$-\frac{4}{7}$
d.
$-\frac{7}{4}$
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Q62 mcq
The coefficient of $x^{2}$ in the expansion of the product $2 - x^{2} 1 + 2x+ 3x^{2}^{6}+ 1 -4x^{2}^{6}$ is $( ){( ) ( ) }$
a.
$107$
b.
$108$
c.
$155$
d.
$106$
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Q63 mcq
The number of values of $k$ for which the system of linear equations $(k+ 2)x+ 10y=k\,&$ $kx+ (k+ 3)y=k-1$ has no solution is
a.
$1$
b.
$2$
c.
$3$
d.
$4$
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Q64 mcq
The differential equation representing the family of ellipses having foci either on the $x$ -axis or on the $y$ -axis, center at the origin and passing through the point $(0, 3)$ is
a.
$xyy' - y^{2} + 9 = 0$
b.
$xyy'' +x(y')^{2} - yy' = 0$
c.
$xyy' +y^{2} -9 = 0$
d.
$x+yy'' = 0$
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Q65 mcq
$1 0 0$ $[ ]$ Let $A= 1 1 0$ and $B=A^{20}$ . Then the sum of the elements of the first column of $B$ is $[ ]$ $1 1 1$
a.
$210$
b.
$211$
c.
$251$
d.
$231$
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Q66 mcq
The mean and the standard deviation $(S. D. )$ of five observations are $9$ and $0$ , respectively. If one of the observation is increased such that the mean of the new set of five observations becomes $10$ , then their $S. D.$ is
a.
$0$
b.
$2$
c.
$4$
d.
$1$
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Q67 mcq
Let $N$ denote the set of all natural numbers. Define two binary relations on $N$ as $R_{1} = {(x,y) \in N \times N : 2x+y= 10}$ and $R_{2} = {(x,y) \in N \times N :x+ 2y= 10}$ . Then
a.
both $R_{1}$ and $R_{2}$ are transitive relations
b.
range of $R_{2}$ is ${1, 2, 3, 4}$
c.
range of $R_{1}$ is ${2, 4, 8}$
d.
both $R_{1}$ and $R_{2}$ are symmetric relations
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Q68 mcq
The locus of the point of intersection of the lines $\sqrt{2}x- y+ 4\sqrt{2}k= 0$ and $\sqrt{2}kx+ky-4 = 0\sqrt{2}$ ( $k$ is any non-zero real parameter) is
a.
an ellipse whose eccentricity is $\frac{1}{\sqrt{3}}$
b.
a hyperbola whose eccentricity is $\sqrt{3}$
c.
a hyperbola with length of its transverse axis $8\sqrt{2}$
d.
an ellipse with length of its major axis $8\sqrt{2}$
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Q69 mcq
If an angle $A$ of a $\Delta ABC$ satisfies $5 cosA+ 3 = 0$ , then the roots of the quadratic equation $9x^{2} + 27x+ 20 = 0$ are
a.
$secA, \, cotA$
b.
$secA, \, tanA$
c.
$tanA, \, cosA$
d.
$sinA, \, secA$
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Q70 mcq
If a circle $C$ , whose radius is $3$ , touches externally the circle $x^{2} +y^{2} + 2x-4y-4 = 0$ at the point $(2, 2)$ , then the length of the intercept cut by this circle $C$ on the $x$ -axis is equal to
a.
$2\sqrt{3}$
b.
$\sqrt{5}$
c.
$3\sqrt{2}$
d.
$2\sqrt{5}$
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Q71 mcq
Let $\frac{1}{x_{1}}, \,\frac{1}{x_{2}}, … , \frac{1}{x_{n}}(x_{i} \neq 0$ for $i= 1, \,2, … . , \,n)$ be in A.P. such that $x_{1} = 4$ and $x_{21} = 20.$ If $n$ is the least positive integer for which $x_{n} > 50$ , then $\sum ^{n}_{i=1}(\frac{1}{x_{i}})$ is equal to
a.
$3$
b.
$\frac{1}{8}$
c.
$\frac{13}{4}$
d.
$\frac{13}{8}$
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Q72 mcq
If the function $f$ defined as $f(x) = \frac{1}{x} - \frac{k-1}{e^{2}^{x}-1}, \,x\neq 0$ is continuous at $x= 0$ , then ordered pair $(k,f(0))$ is equal to
a.
$(2, 1)$
b.
$(3, 1)$
c.
$(3, 2)$
d.
$(\frac{1}{3}, 2)$
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Q73 mcq
If the length of the latus rectum of an ellipse is $4$ units and the distance between a focus and its nearest vertex on the major axis is $\frac{3}{2}$ units, then its eccentricity is
a.
$\frac{2}{3}$
b.
$\frac{1}{2}$
c.
$\frac{1}{9}$
d.
$\frac{1}{3}$
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Q74 mcq
If $p\rightarrow (~\rightarrow p\vee ~q)$ is false, then the truth values of $p$ and $q$ are, respectively
a.
$F, \,F$
b.
$T, \,T$
c.
$F, \,T$
d.
$T, \,F$
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Q75 mcq
$|$ The sum of the intercepts on the coordinate axes of the plane passing through the point $(-2, -2, 2)$ and containing the line joining the points $(1, -1, 2)$ and $(1, 1, 1)$ is
a.
$4$
b.
$12$
c.
$-8$
d.
$-4$
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Q76 mcq
If $\int \frac{tanx}{1+tanx+tan^{2}x}dx=x- \frac{K}{\sqrt{A}}tan^{-1}(\frac{Ktanx+1}{\sqrt{A}})+C$ , ( $C$ is a constant of integration), then the ordered pair $(K,A)$ is equal to
a.
$(2, 1)$
b.
$(2, 3)$
c.
$(-2, 1)$
d.
$(-2, 3)$
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Q77 mcq
The number of numbers between $2, 000$ and $5, 000$ that can be formed with the digits $0, \,1, \,2, \,3, \,4$ (repetition of digits is not allowed) and are multiple of $3$ is
a.
$36$
b.
$30$
c.
$24$
d.
$48$
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Q78 mcq
Let $P$ be a point on the parabola $x^{2} = 4y$ . If the distance of $P$ from the center of the circle $x^{2} +y^{2} + 6x+ 8 = 0$ is minimum, then the equation of the tangent to the parabola at $P$ is
a.
$x+y+ 1 = 0$
b.
$x+ 4y-2 = 0$
c.
$x+ 2y= 0$
d.
$x- y+ 3 = 0$
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Q79 mcq
If $x= \sqrt{2^{cosec}^{-1}^{t}}$ and $y= \sqrt{2^{sec}^{-1}^{t}}, \,(|t| \geq 1),$ then $\frac{dy}{dx}$ is equal to
a.
$\frac{y}{x}$
b.
$-\frac{y}{x}$
c.
$-\frac{x}{y}$
d.
$\frac{x}{y}$
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Q80 mcq
The sum of the first $20$ terms of the series $1 + \frac{3}{2} + \frac{7}{4} + \frac{15}{8} + \frac{31}{16} + …$ is
a.
$39 + \frac{1}{2^{19}}$
b.
$38 + \frac{1}{2^{20}}$
c.
$38 + \frac{1}{2^{19}}$
d.
$39 + \frac{1}{2^{20}}$
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Q81 mcq
A man on the top of a vertical tower observes a car moving at a uniform speed towards the tower on a horizontal road. If it takes $18\, min$ for the angle of depression of the car to change from $30^{\circ}$ to $45^{\circ}$ , then the time taken (in $min$ ) by the car to reach the foot of the tower is
a.
$\frac{9}{2}(\sqrt{3}-1)$
b.
$18(1 + \sqrt{3})$
c.
$18(\sqrt{3}-1)$
d.
$9(1 + \sqrt{3})$
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Q82 mcq
Two different families $A$ and $B$ are blessed with equal number of children. There are $3$ tickets to be distributed amongst the children of these families so that no child gets more than one ticket. If the probability that all the tickets go to the children of the family $B$ is $\frac{1}{12},$ then the number of children in each family is
a.
$6$
b.
$5$
c.
$3$
d.
$4$
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Q83 mcq
Let $\vec{a}= ˆi+ ˆj+ˆk, \,\vec{c}= ˆj- ˆk$ and a vector $\vec{b}$ be such that $\vec{a}\times \vec{b}= \vec{c}$ and $\vec{a}\cdot \vec{b}= 3$ . Then $\vec{b}$ equals
a.
$\frac{11}{3}$
b.
$\frac{11}{\sqrt{3}}$
c.
$\sqrt{\frac{11}{3}}$
d.
$\frac{\sqrt{11}}{3}$
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Q84 mcq
If $f(x) =\int _{0}^{x} t(sinx-sint)dt$ , then
a.
$f^{'''}(x) - f''(x) = cosx-2xsinx$
b.
$f^{'''}(x) +f''(x) - f'(x) = cosx$
c.
$f^{'''}(x) +f''(x) = sinx$
d.
$f^{'''}(x) +f'(x) = cosx-2xsinx$
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Q85 mcq
The least positive integer $n$ for which $(\frac{1+i\sqrt{3}}{1-i\sqrt{3}})^{n} = 1$ is
a.
$2$
b.
$5$
c.
$6$
d.
$3$
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Q86 mcq
If the area of the region bounded by the curves, $y=x^{2}, \,y= \frac{1}{x}$ and the lines $y= 0$ and $x=t(t> 1)$ is $1\, sq. \, unit$ , then $t$ is equal to
a.
$e\frac{2}{3}$
b.
$e\frac{3}{2}$
c.
$\frac{3}{2}$
d.
$\frac{4}{3}$
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Q87 mcq
Let $M$ and $m$ be respectively the absolute maximum and the absolute minimum values of the function, $f(x) = 2x^{3} -9x^{2} + 12x+ 5$ in the interval $[0, 3]$ . Then $M - m$ is equal to
a.
$9$
b.
$4$
c.
$1$
d.
$5$
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Q88 mcq
Let $p,q$ and $r$ be real numbers $(p\neq q,r\neq 0)$ , such that the roots of the equation $\frac{1}{x+p} + \frac{1}{x+q} = \frac{1}{r}$ are equal in magnitude but opposite in sign, then the sum of squares of these roots is equal to
a.
$p^{2} +q^{2}$
b.
$\frac{p^{2}+q^{2}}{2}$
c.
$2(p^{2} +q^{2})$
d.
$p^{2} +q^{2} +r^{2}$
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Q89 mcq
$|$ $-$ Let $A, \,B$ and $C$ be three events, which are pair-wise independent and $E$ denotes the complement of an event $-_{E. IfP(A\cap }_{B\cap }_{C) = 0andP(C) > 0,thenP[(A}_{\cap }_{B)}_{C]is equal to}$ $--$
a.
$P(A )- P(B)$
b.
$P(A)- P(B)$ $\bar{-}--$
c.
$P(A)+P(B)$
d.
$P(A) +P(B)$
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Q90 mcq
$_{x}lim_{\rightarrow 0\rightarrow } \frac{(27+x)-3}{2}_{9-(27+}\frac{1}{3}_{x)^{3}}$ equals
a.
$-\frac{1}{6}$
b.
$\frac{1}{6}$
c.
$\frac{1}{3}$
d.
$-\frac{1}{3}$
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