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JEE Main 2020 (05 Sep Shift 1)

2020 · 75 questions · First 10 Solutions Free
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Q1 nat
A compound microscope consists of an objective lens of focal length $1\, cm$ and an eye piece of focal length $5\, cm$ with a separation of $10\, cm.$ The distance between an object and the objective lens, at which the strain on the eye is minimum is $\frac{n}{40}cm.$ The value of is....... $n$
✓ Accepted Answer: 50

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Q2 mcq
Activities of three radioactive substances $A, \,B$ and are represented by the curves $C A, \,B$ and $C,$ in the figure. Then their half-lives $T\frac{1}{2}(A) :T\frac{1}{2}(B) :T\frac{1}{2} (C)$ are in the ratio:
a.
$2 : \,1 : \,1$
b.
$3 : \,2 : \,1$
c.
$2 : \,1 : \,3$ Correct Answer
d.
$4 : \,3 : \,1$

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Q3 mcq
A physical quantity zdepends on four observables $a, \,b, \,c$ and , as $d z=_{\sqrt{c}d^{3}} .$ The percentage of error in the measurement of $a, \,b, \,c$ and are $d 2%, 1. 5%, 4%$ and $2. 5%$ respectively. The percentage of error in is : $z$
a.
$12. 25%$
b.
$16. 5%$
c.
$13. 5%$
d.
$14. 5%$ Correct Answer

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Q4 mcq
A square loop of side $2a,$ and carrying current is kept in $I XZ$ plane with its centre at origin. A long wire carrying the same current is placed parallel to the -axis and passing through the point $I z (0, \,b, \,0), (b>> \,a)$ . The magnitude of the torque on the loop about -axis is given by. $z$
a.
$\frac{\mu _{0}I^{2}a^{2}}{2\pi b_{2}_{2}}$
b.
$\frac{\mu _{0}I^{2}a^{3}}{2\pi b_{2}^{2}_{3}}$
c.
$\frac{2\mu _{0}Ia}{\pi b}$ Correct Answer
d.
$\frac{2\mu _{0}Ia}{\pi b^{2}}$

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Q5 mcq
Three different processes that can occur in an ideal monoatomic gas are shown in the $P$ vs $V$ diagram. The paths are labelled as $A B,A\rightarrow \rightarrow C$ and $A\rightarrow \rightarrow D$ . The change in internal energies during these process are taken as $E_{AB},E_{AC}$ and $\vec{E}_{AD}$ and the work done as $W_{AB},W_{AC}$ and $W_{AD}$ . The correct relation between these parameters are:
a.
$E_{AB} =E_{AC} <E_{AD},W_{AB} > 0,W_{AC} = 0,W_{AD} < 0$
b.
$E_{AB} =E_{AC} =E_{AD},W_{AB} > 0,W_{AC} = 0,W_{AD} < 0$ Correct Answer
c.
$E_{AB} <E_{AC} <E_{AD},W_{AB} > 0,W_{AC} >W_{AD}$
d.
$E_{AB} >E_{AC} >E_{AD},W_{AB} <W_{AC} <W_{AD}$

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Q6 mcq
Assume that the displacement (s) of air is proportional to the pressure difference $(\Delta p)$ created by a sound wave. Displacement (s) further depends on the speed of sound (v), density of air $(\rho )$ and the frequency (f). If $\Delta p~10 Pa,n~300 m/s,p~1 kg/m^{3} f~1000Hz$ , then s will be of the order of (take the multiplicative constant to be 1 )
a.
$\frac{3}{100}mm$ Correct Answer
b.
$10\, mm$
c.
$\frac{1}{10}mm$
d.
$1\, mm$

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Q7 nat
A beam of electrons of energy E scatters from a target having atomic spacing of $1\,$ ā„«. The first maximum intensity occurs at $\theta = 60^{\circ}.$ Then $E(in \, eV)$ is........ (Planck's constant $h= 6. 64 \times 10^{-34}\, Js, \,1\,eV = 1. 6 \times 10^{-19}J,$ electron mass $m = 9. 1 \times 10^{-31}\, kg$ )
✓ Accepted Answer: 50

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Q8 mcq
A hollow spherical shell at outer radius floats just submerged under the water surface. The inner radius of the $R$ shell is $r\,.$ If the specific gravity of the shell material is $\frac{27}{8}$ with respect to water, the value of is: $r$
a.
$\frac{8}{9}R$ Correct Answer
b.
$\frac{4}{9}R$
c.
$\frac{2}{3}R$
d.
$\frac{1}{3}R$

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Q9 mcq
For a concave lens of focal length , the relation between object and image distance and respectively, $f u v,$ from its pole can best be represented by ( $u=v$ is the reference line):
Question 9 image

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Q10 mcq
With increasing biasing voltage of a photo diode, the photocurrent magnitude:
a.
remains constant
b.
increases initially and after attaining certain value, it decreases
c.
increases linearly
d.
increases initially and saturates finally Correct Answer

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Q11 mcq
In a resonance tube experiment when the tube is filled with water up to a height of $17. 0\, cm ,$ from bottom, it resonates with a given tuning fork. When the water level is raised the next resonance with the same tuning fork occurs at a height of $24. 5\, cm .$ If the velocity of sound in air is $330\,m\,s^{-1},$ the tuning fork frequency is :
a.
$2200\, Hz$
b.
$550\, Hz$
c.
$1100\, Hz$
d.
$3300\, Hz$
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Q12 mcq
A solid sphere of radius $R$ carries a charge $Q+q$ distributed uniformly over its volume. A very small point like piece of it of mass $m$ gets detached from the bottom of the sphere and falls down vertically under gravity. This piece carries charge . If it acquires a speed when it has fallen through a vertical height (see figure), $q ν y$ then (assume the remaining portion to be spherical)
Question 12 image
a.
$v^{2} =y[\frac{qQ}{4\pi \epsilon _{0}R^{2}ym} +g]$
b.
$v^{2} =y[\frac{qQ}{4\pi \epsilon _{0}R(R+y)m} +g]$
c.
$v^{2} = 2y[\frac{QqR}{4\pi \epsilon _{0}(R+y)^{3}m} +g]$
d.
$v^{2} = 2y[\frac{qQ}{4\pi \epsilon _{0}R(R+y)m} +g]$
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Q13 mcq
Two capacitors of capacitances and $C 2C$ are charged to potential differences and $V 2V$ , respectively. These are then connected in parallel in such a manner that the positive terminal of one is connected to the negative terminal of the other. The final energy of this configuration is :
a.
$\frac{25}{6}CV^{2}$
b.
$\frac{3}{2}CV^{2}$
c.
zero
d.
$\frac{9}{2}CV^{2}$
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Q14 mcq
A bullet of mass $5\, gram$ , travelling with a speed of $210\,m\,s^{-1}$ strikes a fixed wooden target. One half of its kinetic energy is converted into heat in the wood. The rise of temperature of the bullet if the specific heat of its material is $0. 030\,(gram \,^{\circ}C)^{-1} (1\,calorie = 4 .2 \times 10^{7}\, ergs)$ close to :
a.
$87. 5^{\circ}C$
b.
$83. 3^{\circ}C$
c.
$119. 2^{\circ}C$
d.
$38. 4^{\circ}C$
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Q15 mcq
An electrical power line, having a total resistance of $2\Omega ,$ delivers $1\, kW$ at $220\,V$ . The efficiency of the transmission line is approximately :
a.
$72%$
b.
$91%$
c.
$85%$
d.
$96%$
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Q16 mcq
An electron is constrained to move along the -axis with a speed of $y 0. 1\,c$ (c is the speed of light) in the presence of electromagnetic wave, whose electric field is $\vec{E}= 30ˆj sin(1. 5 \times 10^{7}t -5 \times 10^{-2}x)\,V\,m^{-1}.$ where in in seconds and $t x$ is im meters.The maximum magnetic force experienced by the electron will be: (given $c = 3 \times 10^{8}\,m\,s^{-1}$ and electron charge $= 1. 6 \times 10^{-19}\, Coloumbs$
a.
$3. 2 \times 10^{-18}\,N$
b.
$2. 4 \times 10^{-18}\,N$
c.
$4. 8 \times 10^{-19}\,N$
d.
$1. 6 \times 10^{-19}\,N$
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Q17 mcq
The value of the acceleration due to gravity is $g_{1}$ at a height $h= \frac{R}{2}$ ( $R=$ radius of the earth) from the surface of the earth. It is again equal to $g_{1}$ at a depth below the surface the earth. The ratio $d (\frac{d}{R})$ equals:
a.
$\frac{4}{9}$
b.
$\frac{5}{9}$
c.
$\frac{1}{3}$
d.
$\frac{7}{9}$
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Q18 nat
A particle of mass $200\, MeV \,c^{-2}$ collides with a hydrogen atom at rest. Soon after the collision, the particle comes to rest, and the atom recoils and goes to its first excited state. The initial kinetic energy of the particle (in $eV$ ) is $\frac{N}{4}.$ The value of $N$ is: (Given the mass of the hydrogen atom to be $1\, GeV \,c^{-2}$ ).........
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Q19 nat
A force $\vec{F} =(ˆi+ 2ˆj+ 3ˆk)\,N$ acts at a point $(4ˆi+ 3ˆj- ˆk)\,m$ . Then the magnitude of torque about the point $(ˆi+ 2ˆj+ ˆk)\,m$ will be $\sqrt{x\,}N -m.$ The value of is.......... $x$
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Q20 mcq
A galvanometer of resistance $G$ is converted into a voltameter of range $0 -1\,V$ by connecting a resistance $R$ in series with it. The additional resistance that should be connected in series with $R_{1}$ to increase the range of the voltmeter to $0 -2V$ will be :
a.
$G$
b.
$R_{1}$
c.
$R_{1}- G$
d.
$R_{1}+G$
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Q21 mcq
A helicopter rises from rest on the ground vertically upwards with a constant acceleration g. A food packet is dropped from the helicopter when it is at a height h. The time taken by the packet to reach the ground is close to [ is the acceleration due to gravity]: $g$
a.
$t= \frac{2}{3}\sqrt{\,} (\frac{h}{g})$
b.
$t= 1. 8\sqrt{\,} (\frac{h}{g})$
c.
$t= 3. 4\sqrt{\,} (\frac{h}{g})$
d.
$t=\sqrt{\frac{2h}{3g}}$
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Q22 mcq
A wheel is rotating freely with an angular speed on a shaft. The moment of inertia of the wheel is and the $\omega I$ moment of inertia of the shaft is negligible. Another wheel of moment of inertia $3I$ initially at rest is suddenly coupled to the same shaft. The resultant fractional loss in the kinetic energy of the system is:
a.
$\frac{5}{6}$
b.
$\frac{1}{4}$
c.
$0$
d.
$\frac{3}{4}$
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Q23 mcq
Number of molecules in a volume of $4\, cm^{3}$ of a perfect monoatomic gas at some temperature T and at a pressure of $2\, cm$ of mercury is close to? (Given, mean kinetic energy of a molecule (at T) is $4 \times 10^{-14}\, erg, \,g = 980\, cm \,s^{-2}$ density of mercury $= 13. 6\,g\, cm^{-3}$ )
a.
$4 .8 \times 10^{18}$
b.
$4. 0 \times 10^{16}$
c.
$5. 8 \times 10^{16}$
d.
$5. 8 \times 10^{18}$
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Q24 mcq
A balloon is moving up in air vertically above a point on the ground. When it is a height $A h_{1},$ a girl standing at a distance d (point B) from A (see figure) sees it at an angle $45^{\circ}$ with respect to the vertical. When the balloon climbs up a further height $h_{2}$ , it is seen at an angle $60^{\circ}$ with respect to the vertical if the girl moves further by a distance $2. 464\,d$ (point C). Then the height $h_{2}$ is (given $tan 30^{\circ}= 0. 5774$ ):
Question 24 image
a.
$1. 464\,d$
b.
$0. 732\,d$
c.
$0 .464 \,d$
d.
$d$
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Q25 nat
Two concentric circular coils, $C_{1}$ and $C_{2}$ , are placed in the $XY$ plane. $C_{1}$ has $500$ turns, and a radius of $1\, cm$ . $C_{2}$ has 200 turns and radius of $20\, cm .\,C_{2}$ carries a time dependent current $I(t) =(5t^{2} -2t+ 3)A$ where is $t$ in s. The emf induced in $C_{1}(in \, mV)$ at the instant $t= 1$ s is $\frac{4}{x}.$ The value of is .......... $x$
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Q26 mcq
Consider the following reaction: $N_{2}O_{4}(g)= 2 NO_{2}(g): \,\Delta H^{0} = +58k$ For each of the following cases $(a, \,b)$ , the direction in which the equilibrium shifts is: (a) Temperature is decreased. (b) Pressure is increased by adding $N_{2}$ at constant T.
a.
(a) towards product, (b) towards reactant
b.
(a) towards reactant, (b) towards product
c.
(a) towards reactant, (b) no change
d.
(a) towards product, (b) no change
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Q27 mcq
The potential energy curve for the $H_{2}$ molecule as a function of internuclear distance is:
Question 27 image
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Q28 mcq
An Ellingham diagram provides information about:
a.
the conditions of $pH$ and potential under which a species is thermodynamically stable.
b.
the temperature dependence of the standard Gibbs energies of formation of some metal oxides.
c.
the pressure dependence of the standard electrode potentials of reduction reactions involved in the extraction of metals.
d.
the kinetics of the reduction process.
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Q29 nat
The number of chiral carbon(s) present in peptide, lle-Arg-Pro, is ................
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Q30 mcq
The increasing order of basicity of the following compounds is :
Question 30 image
a.
$(A) < (B) < (C) < (D)$
b.
$(B) < (A) < (D) < (C)$
c.
$(D) < (A) < (B) < (C)$
d.
$(B) < (A) < (C) < (D)$
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Q31 mcq
The increasing order of the acidity of the -hydrogen of the following compounds is:$\alpha$ $(A)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(B)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(C)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(D)$
Question 31 image
a.
$(D) < (C) < (A) < (B)$
b.
$(B) < (C) < (A) < (D)$
c.
$(A) < (C) < (D) < (B)$
d.
$(C) < (A) < (B) < (D)$
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Q32 mcq
Which of the following derivatives of alcohols is unstable in an aqueous base?
Question 32 image
d.
$RO -CMe_{3}$
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Q33 nat
The minimum number of moles of $O_{2}$ required for complete combustion of 1 mole of propane and 2 moles of butane is..............
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Q34 mcq
Identify the correct molecular picture showing what happens at the critical micellar concentration $(CMC)$ of an aqueous solution of a surfactant
Question 34 image
a.
$(D)$
b.
$(B)$
c.
$(A)$
d.
$(C)$
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Q35 mcq
The condition that indicates a polluted environment is:
a.
eutrophication
b.
$0. 03%$ of $CO_{2}$ in the atmosphere
c.
BOD value of 5 ppm
d.
$pH$ of rain water to be 5.6
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Q36 mcq
In the sixth period, the orbitals that are filled are :
a.
$6s, \,4f, \,5d, \,6p$
b.
$6s, \,5d, \,5f, \,6p$
c.
$6s, \,5f, \,6d, \,6p$
d.
$6s, \,6p, \,6d, \,6f$
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Q37 nat
The total number of coordination sites in ethylenediaminetetraacetate ( $EDTA^{4-}$ ) is ...................
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Q38 mcq
The structure of $PCl_{5}$ in the solid state is :
a.
tetrahedral $[PC_{4}]^{+}$ and octahedral $[PCl_{6}]^{-}$
b.
square planar $[PCl_{4}]^{+}$ and octahedral $[PCl_{6}]^{-}$
c.
square pyramidal
d.
trigonal bipyramidal
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Q39 mcq
Which of the following is not an essential amino acid?
a.
Tyrosine
b.
Leucine
c.
Valine
d.
Lysine
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Q40 mcq
The difference between the radii of $3^{rd}$ and $4^{th\,}$ orbits of $L^{2+}_{i}$ is $\Delta R_{1}$ . The difference between the radii of $3^{rd}$ and $4^{th\,}$ orbits of $He^{+} \Delta R_{2}.$ Ratio $\Delta R_{1} :\Delta R_{2}$ is :
a.
$8 : 3$
b.
$3 : 8$
c.
$2 : \,3$
d.
$3 : \,2$
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Q41 mcq
The equation that represents the water-gas shift reaction is :
a.
$CH_{4}(g) + H_{2}O(g)\frac{1270\,K}{Ni}CO(g) + 3H_{2}(g)$
b.
$-2C(s) + O_{2}(g) + 4N_{2}(g)^{1273K} 2 CO(g) + 4N_{2}(g)$ $CO(g) + H$
c.
$-C(s) + H_{2}O(g)^{1270\,K}_{2}(g)$
d.
$-CO(g) + H_{2}O(g)\,_{c\vec{a}}^{673K}_{tal\vec{y}st} \, C\vec{O}_{2}(g)\, + \,H_{2}(g)$
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Q42 nat
An oxidation-reduction reaction in which 3 electrons are transferred has a $\Delta G^{0}$ of $17. 37\, kJ \, mol^{-1}$ at $25^{\circ}C.$ The value of $E^{o}_{cell}$ (in V) is $_______ \times 10^{-2}$ . $(1F = 96500\,C\, mol^{-1})$
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Q43 mcq
The values of the crystal field stabilization energies for a high spin $d^{6}$ metal ion in octahedral and tetrahedral fields, respectively, are:
a.
$-0 .4\Delta _{o}$ and $-0. 6\Delta _{t}$
b.
$-2 .4\Delta _{o}$ and $-0. 6\,\Delta _{t}$
c.
$-1 .6\Delta _{o}$ and $-0. 4\Delta _{t}$
d.
$-0 .4\Delta _{o}$ and $-0 .27\Delta _{t}$
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Q44 mcq
A flask contains a mixture of compounds and . Both compounds decompose by first-order kinetics. The $A B$ half-lives for and are $A B 300\,s$ and $180\,s$ , respectively. If the concentrations of and are equal initially, the $A B$ time required for the concentration of A to be four times that of (in s) is : $B (Use \, ln \,2 = 0. 693)$
a.
$180$
b.
$900$
c.
$300$
d.
$120$
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Q45 mcq
If a person is suffering from the deficiency of nor-adrenaline, what kind of drug can be suggested?
a.
Anti-inflammatory
b.
Antidepressant
c.
Antihistamine
d.
Analgesic
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Q46 nat
A soft drink was bottled with a partial pressure of $CO_{2}$ of 3 bar over the liquid at room temperature. The partial pressure of $CO_{2}$ over the solution approaches a value of 30 bar when $44\,g$ of $CO_{2}$ is dissolved in $1\, kg$ of water at room temperature. The approximate $pH$ of the soft drink is ___________ $\times 10^{-1}$ . (First dissociation constant of $H_{2}CO_{3} = 4. 0 \times 10^{-7}; \, log 2 = 0. 3;$ density of the soft drink $= 1\,g\, mL^{-1}$ )
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Q47 mcq
In the following reaction sequence the major products and are : $A B$
Question 47 image
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Q48 mcq
The correct electronic configuration and spin-only magnetic moment (BM) of $Gd^{3+}(Z = 64),$ respectively, are :
a.
$[Xe]4f^{7}$ and $8. 9$
b.
$[Xe]4f^{7}$ and $7. 9$
c.
$[Xe]5f^{7}$ and $8. 9$
d.
$[Xe]5f^{7}$ and $7. 9$
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Q49 mcq
The most appropriate reagent for conversion of $C_{2}H_{5}CN$ into $CH_{3}CH_{2}CH_{2}NH_{2}$ is :
a.
$NaBH_{4}$
b.
$CaH_{2}$
c.
$LiAlH_{4}$
d.
$Na(CN) BH_{3}$
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Q50 mcq
A diatomic molecule $X_{2}$ has a body-centred cubic $(bcc)$ structure with a cell edge of $300\, pm.$ The density of the molecule is $6. 17\, gcm^{-3}.$ The number of molecules present in $200\,g$ of $X_{2}$ is : (Avogadro constant $(N_{A}) = 6 \times 10^{23} mol^{-1}$ )
a.
$40\,N_{A}$
b.
$8\,N_{A}$
c.
$4\,N_{A}$
d.
$2\,N_{A}$
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Q51 mcq
$|$ The mean and variance of observations are and $7 8 16$ , respectively. If five observations are $2, 4, 10, 12, 14$ then the absolute difference of the remaining two observations is :
a.
$1$
b.
$4$
c.
$2$
d.
$3$
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Q52 mcq
If $\int (e^{2x} + 2e^{x} - e^{-x} -1)e^{(e^{x}+e^{-}^{x})}dx=g(x)e^{(e^{x}+e^{-}^{x})} +c,$ where is a constant of integration, then $c g(0)$ is
a.
$e$
b.
$e^{2}$
c.
$1$
d.
$2$
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Q53 mcq
The value of $\int _{-}^{\pi }\frac{2}{2}_{\pi } \frac{1}{1+e^{sin}^{x}}dx$ is :
a.
$\frac{\pi}{4}$
b.
$\pi$
c.
$\frac{\pi}{2}$
d.
$\frac{3\pi}{2}$
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Q54 nat
The number of words, with or without meaning, that can be formed by taking 4 letters at a time from the letters of the word 'SYLLABUS' such that two letters are distinct and two letters are alike, is
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Q55 mcq
If the minimum and the maximum values of the function $f :[\frac{\pi}{4}, \frac{\pi}{2}]\rightarrow \rightarrow R,$ defined by $-sin^{2} \theta -1 -sin^{2} \theta 1$ $f(\theta ) = -cos^{2} \theta -1 -cos^{2} \theta 1$ are $m$ and $M$ respectively, then the ordered pair $(m, \,M)$ is equal to : $12 10 -2$
a.
$(0, 2\sqrt{2})$
b.
$(-4, 0)$
c.
$(-4, \,4)$
d.
$(0, 4)$
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Q56 mcq
If the common tangent to the parabolas, $y^{2} = 4\,x and x^{2} = 4\,y$ also touches the circle, $x^{2} +y^{2} =c^{2},$ then is $c$ equal to :
a.
$\frac{1}{2\sqrt{2}}$
b.
$\frac{1}{\sqrt{2}}$
c.
$\frac{1}{4}$
d.
$\frac{1}{2}$
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Q57 mcq
If is the sum of the first 10 terms of the series, $S tan^{-1}(\frac{1}{3})+ tan^{-1}(\frac{1}{7})+ tan^{-1}(\frac{1}{13})+ tan^{-1}(\frac{1}{21})+ … …$ then $tan(S)$ is equal to :
a.
$\frac{5}{6}$
b.
$\frac{5}{11}$
c.
$-\frac{5}{6}$
d.
$\frac{10}{11}$
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Q58 mcq
If $y=y(x)$ is the solution of the differential equation $\frac{5+e^{x}}{2+y} \cdot \frac{dy}{dx} +e^{x} = 0$ satisfying $y(0) = 1$ then value of $y(log_{e}13)$ is
a.
$1$
b.
$-1$
c.
$0$
d.
$2$
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Q59 mcq
A survey shows that $73%$ of the persons working in an office like coffee, whereas $65%$ like tea. If denotes $x$ the percentage of them, who like both coffee and tea, then cannot be: $x$
a.
$63$
b.
$36$
c.
$54$
d.
$38$
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Q60 mcq
The negation of the Boolean expression $x\leftrightarrow ~y$ is equivalent to:
a.
$(~x\wedge y) \vee (~x\wedge ~y)$
b.
$(x\wedge y) \vee (~x\wedge ~y)$
c.
$(x\wedge ~y) \vee (~x\wedge y)$
d.
$(x\wedge y) \wedge (~x\vee ~y)$
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Q61 mcq
If is the positive root of the equation, $\alpha p(x) =x^{2} - x-2 = 0$ , then $_{x}lim_{\rightarrow \rightarrow \alpha ^{+}} \frac{\sqrt{1-cosp(x)}}{x+\alpha -4}$ is equal to
a.
$\frac{3}{2}$
b.
$\frac{3}{\sqrt{2}}$
c.
$\frac{1}{\sqrt{2}}$
d.
$\frac{1}{2}$
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Q62 mcq
$-$ If the four complex numbers $z,z,z-2 Re (z)$ and $z-2 Re (z)$ represent the vertices of a square of side $4$ units in the Argand plane, then $\bar{|}z|$ is equal to :
a.
$4\sqrt{2}$
b.
$4$
c.
$2\sqrt{2}$
d.
$2$
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Q63 mcq
If $3^{2 sin 2\alpha -1}, 14$ and $3^{4-2 sin 2\alpha }$ are the first three terms of an A.P. for some , then the sixth term of this A.P. is $\alpha$
a.
$66$
b.
$81$
c.
$65$
d.
$78$
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Q64 mcq
If the co-ordinates of two points and are $A B (\sqrt{7}, 0)$ and $(-\sqrt{7}, 0)$ respectively and is any point on the $P$ conic, $9x^{2} + 16y^{2} = 144,$ then $PA+PB$ is equal to :
a.
$16$
b.
$8$
c.
$6$
d.
$9$
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Q65 mcq
The product of the roots of the equation $9x^{2} -18 x + 5 = 0$ is :
a.
$\frac{5}{9}$
b.
$\frac{25}{81}$
c.
$\frac{5}{27}$
d.
$\frac{25}{9}$
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Q66 nat
If the line, $2\,x- y+ 3 = 0$ is at a distance $\frac{1}{\sqrt{5}}$ and $\frac{2}{\sqrt{5}}$ from the lines $4x-2y+\alpha = 0$ and $6x-3y+\beta = 0$ respectively, then the sum of all possible values of $\alpha$ and is ____________. $\beta$
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Q67 mcq
$k_{1}(x- \pi )^{2}-1, x\leq \pi$ If the function $f(x) ={$ is twice differentiable, then the ordered pair $(k_{1},k_{2})$ is equal $k_{2}cosx, x>\pi$ to:
a.
$(\frac{1}{2}, 1)$
b.
$(1, 0)$
c.
$(\frac{1}{2}, -1)$
d.
$(1, 1)$
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Q68 mcq
$| |$ If $(a, \,b, \,c)$ is the image of the point $(1, 2, -3)$ in the line, $\frac{x+1}{2} = \frac{y-3}{-2} = \frac{z}{-1},$ then $a+b+c$ is equal to:
a.
$2$
b.
$-1$
c.
$3$
d.
$1$
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Q69 nat
Let $f(x)=x\cdot [\frac{x}{2}],$ for $-10 <x< 10,$ where $[t]$ denotes the greatest integer function. Then the number of points of discontinuity of $f(x)$ is equal to
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Q70 nat
Four fair dice are thrown independently 27 times. Then the expected number of times, at least two dice show up a three or a five, is
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Q71 mcq
If the point $P$ on the curve, $4x^{2} + 5y^{2} = 20$ is farthest from the point $Q(0, -4)$ , then $PQ^{2}$ is equal to
a.
$36$
b.
$48$
c.
$21$
d.
$29$
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Q72 nat
The natural number $m$ , for which the coefficient of in the binomial expansion of $x (x^{m} + \frac{1}{x^{2}})^{22}$ is 1540, is
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Q73 mcq
Let $\lambda \in R$ . The system of linear equations $2x_{1}-4x_{2}+\lambda x_{3} = 1$ $x_{1}-6x_{2}+x_{3} = 2$ $\lambda x_{1}-10x_{2}+ 4x_{3} = 3$ is inconsistent for :
a.
exactly one positive value of $\lambda$
b.
exactly one negative value of $\lambda$
c.
every value of $\lambda$
d.
exactly two values of $\lambda$
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Q74 mcq
If the volume of a parallelopiped, whose coterminous edges are given by the vectors $\vec{a}= ˆi+ ˆj+nˆk$ , $\vec{b}= 2ˆi + \,4ˆj -\,nˆk$ and, $\vec{c}= ˆi +nˆj+ 3ˆk(n \geq 0)$ is $158$ cubic units, then :
a.
$\vec{a}\cdot \vec{c}= 17$
b.
$\vec{b}\cdot \vec{c}= 10$
c.
$n= 7$
d.
$n= 9$
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Q75 mcq
If $2^{10} + 2^{9} \cdot 3^{1} + 2^{8} \cdot 3^{2} + … … + 2 \cdot 3^{9} + 3^{10} =S-2^{11}$ , then is equal to $S$
a.
$3^{11} -2^{12}$
b.
$3^{11}$
c.
$\frac{3^{11}}{2} + 2^{10}$
d.
$2. 3^{11}$
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