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JEE Main 2020 (07 Jan Shift 2)

2020 · 75 questions · First 10 Solutions Free
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Q1 mcq
A stationary observer receives sound from two identical tuning forks, one of which approaches and the other one recedes with the same speed (much less than the speed of sound). The observer hears $2\,beats/sec$ . The oscillation frequency of each tuning fork is $v_{0} = 1400\,Hz$ and the velocity of sound in air is $350\,m/s$ . The speed of each tuning fork is close to:
a.
$\frac{1}{2}m/s$
b.
$1m/s$
c.
$\frac{1}{4}m/s$ Correct Answer
d.
$\frac{1}{8}m/s$

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Q2 mcq
An emf of $20\,V$ is applied at time $t= 0$ to a circuit containing in series $10\,mH$ inductor and $5\,\Omega$ resistor. The ratio of the currents at time $t= \infty$ and at $t= 40\,s$ is close to: (Take $e^{2} = 7.389$ )
a.
$1.06$ Correct Answer
b.
$1.15$
c.
$1.46$
d.
$0.84$

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Q3 mcq
In a building there are $15$ bulbs of $45W$ , $15$ bulbs of $100W, 15$ small fans of $10W$ and $2$ heaters of $1kW$ . The voltage of electric main supply is $220V$ . The minimum fuse capacity (rated value) of the building will be:
a.
$5A$
b.
$25A$
c.
$15A$
d.
$20A$ Correct Answer

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Q4 nat
$M$ grams of steam at $100^{o}C$ is mixed with $200g$ of ice at its melting point in a thermally insulated container. If it produces liquid water at $40^{o}C$ [heat of vaporization of water is $540cal/g$ and heat of fusion of ice is $80cal/g$ ], the value of $M$ is ________
✓ Accepted Answer: 40

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Q5 nat
The balancing length for a cell is $560cm$ in a potentiometer experiment. When an external resistance of $10\Omega$ is connected in parallel to the cell, the balancing length changes by $60cm$ . If the internal resistance of the cell is $\frac{n}{10}\Omega$ , where n is an integer then value of n is ________
✓ Accepted Answer: 12

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Q6 mcq
A thin lens made of glass (refractive index $= 1.5$ ) of focal length $f = 16cm$ is immersed in a liquid of refractive index $1.42$ . If its focal length in liquid is $f_{l}$ , then the ratio $f_{l}/f$ is closest to the integer:
a.
$1$
b.
$9$ Correct Answer
c.
$5$
d.
$17$

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Q7 mcq
In the figure, potential difference between $A$ and $B$ is:
Question 7 image
a.
$10\,V$ Correct Answer
b.
$5\,V$
c.
$15\,V$
d.
$0 V$

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Q8 nat
A $60pF$ capacitor is fully charged by a $20V$ supply. It is then disconnected from the supply and is connected to another uncharged $60pF$ capacitor in parallel. The electrostatic energy that is lost in this process by the time the charge is redistributed between them is (in $nJ$ ) ________
✓ Accepted Answer: 6

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Q9 mcq
An ideal fluid flows (laminar flow) through a pipe of non-uniform diameter. The maximum and minimum diameters of the pipes are $6.4cm$ and $4.8cm$ , respectively. The ratio of the minimum and the maximum velocities of fluid in this pipe is:
a.
$\frac{9}{16}$ Correct Answer
b.
$\frac{\sqrt{3}}{2}$
c.
$\frac{3}{4}$
d.
$\frac{81}{256}$

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Q10 mcq
An elevator in a building can carry a maximum of $10$ persons, with the average mass of each person being $68\,kg$ . The mass of the elevator itself is $920\,kg$ and it moves with a constant speed of $3\,m/s$ . The frictional force opposing the motion is $6000\,N$ . If the elevator is moving up with its full capacity, the power delivered by the motor to the elevator $(g = 10m/s^{2})$ must be at least:
a.
$56300W$
b.
$62360W$
c.
$48000W$
d.
$66000W$ Correct Answer

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Q11 mcq
The figure gives experimentally measured $B$ vs. $H$ variation in a ferromagnetic material. The retentivity, coercivity and saturation, respectively, of the material are:
a.
$1.5T, 50A/m$ and $1.0T$
b.
$1.5T, 50A/m$ and $1.0T$
c.
$150A/m, 1.0T$ and $1.5T$
d.
$1.0T, 50A/m$ and $1.5T$
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Q12 mcq
The activity of a radioactive sample falls from $700s^{-1}$ to $500s^{-1}$ in $30$ minutes. Its half life is close to:
a.
$72min$
b.
$62min$
c.
$66min$
d.
$52min$
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Q13 nat
$||$ The sum of two forces $\vec{P}$ and $\vec{Q}$ is $\vec{R}$ such that $\vec{R} = \vec{P}$ . Find the angle between resultant of $2\vec{P}$ and $\vec{Q}$ and $\vec{Q}$ , ________
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Q14 mcq
An electron (of mass $m$ ) and a photon have the same energy $E$ in the range of a few $eV$ . The ratio of the de- Broglie wavelength associated with the electron and the wavelength of the photon is ( $c =$ speed of light in vacuum)
a.
$\frac{1}{c}(\frac{2E}{m})^{1/2}$
b.
$c(2mE)^{1/2}$
c.
$\frac{1}{c}(\frac{E}{2m})^{1/2}$
d.
$(\frac{E}{2m})^{1/2}$
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Q15 mcq
Given, $B$ is magnetic field induction, and $\mu _{0}$ is the magnetic permeability of vacuum. The dimension of $_{2\mu _{0}}$ is:
a.
$MLT^{-2}$
b.
$ML^{2}T^{-1}$
c.
$ML^{2}T^{-2}$
d.
$ML^{-1}T^{-2}$
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Q16 mcq
Two ideal Carnot engines operate in cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures, $T_{1}$ and $T_{2}$ . The temperature of the hot reservoir of the first engine is $T_{1}$ and the temperature of the cold reservoir of the second engine is $T_{2}$ . $T$ is temperature of the sink of first engine which is also the source for the second engine. How is $T$ related to $T_{1}$ and $T_{2}$ , if both the engines perform equal amount of work?
a.
$T = \frac{2T_{1}T_{2}}{T_{1}+T_{2}}$
b.
$T = \frac{T_{1}+T_{2}}{2}$
c.
$T = \sqrt{TT}_{1}_{2}$
d.
$T = 0$
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Q17 mcq
Under an adiabatic process, the volume of an ideal gas gets doubled. Consequently, the mean collision time between the gas molecule changes from $τ_{1}$ to $τ_{2}$ . If $\frac{C}{C_{v}}^{P} =\gamma$ for this gas then a good estimate for $\frac{τ}{τ_{1}}^{2}$ is given by
a.
$2$
b.
$\frac{1}{2}$
c.
$(\frac{1}{2})^{\gamma }$
d.
$( \frac{1}{2})\frac{\gamma +1}{2}$
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Q18 mcq
The electric field of a plane electromagnetic wave is given by $\vec{E} =E_{0} \frac{ˆi+ˆj}{\sqrt{2}}cos(kz+\omega t)$ . At $t= 0$ , a positively charged particle is at the point $(x,y,z) =(0, 0, \frac{\pi}{k} )$ . If its instantaneous velocity at $(t= 0)$ is $v_{0}ˆk$ , the force acting on it due to the wave is:
a.
parallel to $\frac{ˆi+ˆj}{\sqrt{2}}$
b.
zero
c.
antiparallel to $\frac{ˆi+ˆj}{\sqrt{2}}$
d.
parallel to $ˆk$
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Q19 mcq
In a Young’s double slit experiment, the separation between the slits is $0.15mm$ . In the experiment, a source of light of wavelength $589nm$ is used and the interference pattern is observed on a screen kept $1.5m$ away. The separation between the successive bright fringes on the screen is:
a.
$6.9mm$
b.
$3.9mm$
c.
$5.9mm$
d.
$4.9mm$
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Q20 nat
Consider a uniform cubical box of side a on a rough floor that is to be moved by applying minimum possible force $F$ at a point $b$ above its centre of mass (see figure). If the coefficient of friction is $\mu = 0.4$ , the maximum possible value of $100 \times \frac{b}{a}$ for a box not to topple before moving is ________
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Q21 mcq
A box weighs $196N$ on a spring balance at the north pole. Its weight recorded on the same balance if it is shifted to the equator is close to (Take $g = 10ms^{-2}$ at the north pole and the radius of the earth $= 6400km$ ):
a.
$195.66N$
b.
$194.32N$
c.
$194.66N$
d.
$195.32N$
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Q22 mcq
A mass of $10\,kg$ is suspended by a rope of length $4\,m$ , from the ceiling. A force $F$ is applied horizontally at the mid-point of the rope such that the top half of the rope makes an angle of $45^{\circ}$ with the vertical. Then $F$ equals: (Take $g = 10\,m\,s^{-2}$ and the rope to be massless)
a.
$100N$
b.
$90N$
c.
$70N$
d.
$75N$
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Q23 mcq
A particle of mass $m$ and charge $q$ has an initial velocity $\vec{v}=v_{0}ˆj$ . If an electric field $\vec{E} =E_{0}ˆi$ and magnetic field $\vec{B}=B_{0}ˆi$ act on the particle, its speed will double after a time
a.
$\frac{2mv_{0}}{qE_{0}}$
b.
$\frac{3mv_{0}}{qE_{0}}$
c.
$\frac{\sqrt{3}mv_{0}}{qE_{0}}$
d.
$\frac{\sqrt{2}mv_{0}}{qE_{0}}$
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Q24 mcq
A planar loop of wire rotates in a uniform magnetic field. Initially, at $t= 0$ , the plane of the loop is perpendicular to the magnetic field. If it rotates with a period of $10s$ about an axis in its plane then the magnitude of induced emf will be maximum and minimum, respectively at:
a.
$2.5\,s$ and $7.5\,s$
b.
$2.5\,s$ and $5.0\,s$
c.
$5.0\,s$ and $7.5\,s$
d.
$5.0\,s$ and $10. 0\,s$
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Q25 mcq
Mass per unit area of a circular disc of radius a depends on the distance $r$ from its centre as $\sigma (r) =A+Br$ . The moment of inertia of the disc about the axis, perpendicular to the plane and passing through its centre is:
a.
$2\pi a^{4}( \frac{A}{4} + \frac{aB}{5})$
b.
$2\pi a^{4}( \frac{aA}{4} + \frac{B}{5})$
c.
$\pi a^{4}(\frac{A}{4} + \frac{aB}{5} )$
d.
$2\pi a^{4}(\frac{A}{4} + \frac{B}{5} )$
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Q26 mcq
Identify the correct labels of $A, B$ and $C$ in the following graph from the options given below: Root mean square speed $(V_{rms});$ most proable speed $(V_{mp});$ Average speed $(V_{av})$
Question 26 image
a.
$A -V_{mp}; B -V_{rms}; C -V_{av}$
b.
$A -V_{av}; B -V_{rms}; C -V_{mp}$
c.
$A -V_{rms}; B -V_{mp}; C -V_{av}$
d.
$A -V_{mp}; B -V_{av}; C -V_{rms}$
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Q27 mcq
For the following reactions where, $k_{s}$ and $k_{e}$ , are respectively, the rate constants for substitution and elimination, and $\mu$ $= \frac{k_{s}}{k_{e}}$ , the correct option is ________
Question 27 image
a.
$\mu$ $_{B} >$ $\mu$ $_{A}$ and $k_{e}(A) > k_{e}(B)$
b.
$\mu$ $_{A} >$ $\mu$ $_{B}$ and $k_{e}(B) > k_{e}(A)$
c.
$\mu$ $_{B} >$ $\mu$ $_{A}$ and $k_{e}(B) > k_{e}(A)$
d.
$\mu$ $_{A} >$ $\mu$ $_{B}$ and $k_{e}(A) > k_{e}(B)$
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Q28 mcq
Two open beakers one containing a solvent and the other containing a mixture of that solvent with a non volatile solute are together sealed in a container. Over time:
a.
the volume of the solution increases and the volume of the solvent decreases
b.
the volume of the solution decreases and the volume of the solvent increases
c.
the volume of the solution and the solvent does not change the volume of the solution does not
d.
change and the volume of the solvent decreases
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Q29 mcq
The equation that is incorrect is:
a.
$(\Lambda ^{0}_{m})_{KBr} - (\Lambda ^{0}_{m})_{NaCl} =(\Lambda ^{0}_{m})_{KBr} - (\Lambda ^{0}_{m})_{KCl}$
b.
$(\Lambda ^{0}_{m})_{KG} - (\Lambda ^{0}_{m})_{KQ} =(\Lambda ^{0}_{m})_{NaG} - (\Lambda ^{0}_{m})_{NaQ}$
c.
$(\Lambda ^{0}_{m})_{H_{2}O} =(\Lambda ^{0}_{m})_{HCl} +(\Lambda ^{0}_{m})_{NaOH} - (\Lambda ^{0}_{m})_{NaCl}$
d.
$(\Lambda ^{0}_{m})_{NaBr} - (\Lambda ^{0}_{m})_{Nal} =(\Lambda ^{0}_{m})_{KBr} - (\Lambda ^{0}_{m})_{KI}$
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Q30 mcq
The bond order and the magnetic characteristic of $CN^{-}$ are
a.
$2\frac{1}{2},$ diamagnetic
b.
$3,$ diamagnetic
c.
$3,$ paramagnetic
d.
$2\frac{1}{2},$ paramagnetic
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Q31 mcq
Consider the following reactions: Which of these reactions are possible?
Question 31 image
a.
$(a)$ and $(b)$
b.
$(a)$ and $(d)$
c.
$(b), (c)$ and $(d)$
d.
$(b)$ and $(d)$
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Q32 mcq
The number of possible optical isomers for the complexes $MA_{2}B_{2}$ with $sp^{3}$ and $dsp^{2}$ hybridized metal atom, respectively, is: Note: $A$ and $B$ are unidentate neutral and unidentate monoanionic ligands, respectively.
a.
$0$ and $2$
b.
$2$ and $2$
c.
$0$ and $0$
d.
$0$ and $1$
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Q33 nat
Consider the following reactions: $NaCl + K_{2}Cr_{2}O_{7}+ H_{2}SO_{4} \rightarrow (A)+\rightarrow$ side products $(Conc.)$ $(A) + NaOH \rightarrow (B)+\rightarrow$ side products $(B) + H_{2}SO_{4} + H_{2}O_{2} \rightarrow (C)+\rightarrow$ side products $(dilute)$ The sum of the total number of atoms in one molecule each of $(A), (B)$ and $(C)$ is ________
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Q34 mcq
In the following reaction sequence, structures of $A$ and $B$ are, respectively
Question 34 image
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Q35 mcq
For the reaction $2H_{2}(g) + 2NO(g) \rightarrow N\rightarrow_{2}(g) + 2H_{2}O(g)$ the observed rate expression is, rate $= k_{f}[NO]^{2}[H_{2}]$ . The rate expression for the reverse reaction is:
a.
$k_{b}[N_{2}][H_{2}O]^{2}$
b.
$k_{b}[N_{2}][H_{2}O]^{2}/[NO]$
c.
$k_{b}[N_{2}][H_{2}O]$
d.
$k_{b}[N_{2}][H_{2}O]^{2}/[H_{2}]$
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Q36 mcq
In the following reaction sequence, the major product $B$ is
Question 36 image
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Q37 nat
The number of $sp^{2}$ hybridised carbons present in “Aspartame” is
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Q38 mcq
Which of the following statements is correct?
a.
Gluconic acid can form cyclic (acetal/hemiacetal) structure
b.
Gluconic acid is a dicarboxylic acid
c.
Gluconic acid is a partial oxidation product of glucose
d.
Gluconic acid is obtained by oxidation of glucose with $HNO_{3}$
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Q39 mcq
In the following reactions, products $(A)$ and $(B)$ , respectively, are: $NaOH + Cl_{2} \rightarrow (A) + side\,products\rightarrow$ $(hot\,and\,conc. )$ $Ca(OH)_{2}+ Cl_{2} (B) + side\,products$ $(dry)$
a.
$NaClO_{3}$ and $\vec{C}a(OCl)_{2}$
b.
$NaClO_{3}$ and $Ca(ClO_{3})_{2}$
c.
$NaOCl$ and $Ca(OCl)_{2}$
d.
$NaOCl$ and $Ca(ClO_{3})_{2}$
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Q40 nat
The standard heat of formation $(\Delta _{f}H_{298}^{0} )$ of ethane (in $kJ/mol$ ), if the heat of combustion of ethane, hydrogen and graphite are $-1560, -393.5$ and $-286\,kJ/mol$ , respectively is ________
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Q41 mcq
Among statements $(a) -(d)$ , the correct ones are: $(a)$ Decomposition of hydrogen peroxide gives di-oxygen. $(b)$ Like hydrogen peroxide, compounds, such as $KClO_{3}, Pb(NO_{3})$ and $NaNO_{3}$ When heated liberate di- oxygen. $(c) 2$ -Ethylanthraquinone is useful for the industrial preparation of hydrogen peroxide. $(d)$ Hydrogen peroxide is used for the manufacture of sodium perborate.
a.
$(a), (b), (c)$ and $(d)$
b.
$(a), (b),$ and $(c)$ only
c.
$(a), (c),$ and $(d)$ only
d.
$(a)$ and $(c)$ only
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Q42 mcq
The redox reaction among the following is
a.
formation of ozone from atmospheric oxygen in the presence of sunlight
b.
reaction of $[Co(H_{2}O)_{6}]Cl_{3}$ with $AgNO_{3}$
c.
reaction of $H_{2}SO_{4}$ with $NaOH$
d.
combination of dinitrogen with dioxygen at $2000K$
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Q43 mcq
The correct order of stability for the following alkoxides is:
Question 43 image
a.
$(B) > (A) > (C)$
b.
$(C) > (B) > (A)$
c.
$(C) > (A) > (B)$
d.
$(B) > (C) > (A)$
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Q44 mcq
The ammonia $(NH_{3})$ released on quantitative reaction of $0.6\,g$ urea $(NH_{2}CONH_{2})$ with sodium hydroxide $(NaOH)$ can be neutralized by
a.
$200\,ml$ of $0.4\,NHCl$
b.
$200\,ml$ of $0.2\,NHCl$
c.
$100\,ml$ of $0.2\,NHCl$
d.
$100\,ml$ of $0.1\,NHCl$
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Q45 mcq
The refining method used when the metal and the impurities have low and high melting temperatures, respectively, is
a.
liquation.
b.
vapour phase refining.
c.
zone refining.
d.
distillation.
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Q46 mcq
Among the statements $(a) -(d)$ , the incorrect ones are: $(a)$ Octahedral $Co(III)$ complexes with strong field ligands have very high magnetic moments $(b)$ When $\Delta _{0} <P$ , the d-electron configuration of $Co(III)$ in an octahedral complex is $t^{4}_{eg}e^{2}_{g}$ $(c)$ Wavelength of light absorbed by $[Co(en)_{3}]^{3+}$ is lower than that of $[CoF_{6}]^{3-}$ $(d)$ If the $\Delta _{0}$ for an octahedral complex of $Co(III)$ is $18,000cm^{-1}$ , the $\Delta _{t}$ for its tetrahedral complex with the same ligand will be $16,000cm^{-1}$ .
a.
$(a)$ and $(d)$ only
b.
$(c)$ and $(d)$ only
c.
$(a)$ and $(b)$ only
d.
$(b)$ and $(c)$ only
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Q47 nat
The flocculation value of $HCl$ for arsenic sulphide $sol$ is $30\,mmolL^{-1}$ . If $H_{2}SO_{4}$ is used for the flocculation of arsenic sulphide, the amount, in grams, of $H_{2}SO_{4}$ in $250ml$ required for the above purpose is ________ (molecular mass of $H_{2}SO_{4} = 98\,g/mol$
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Q48 mcq
Within each pair of elements $F$ and $Cl$ , $S$ and $Se$ , and $Li$ and $Na$ , respectively, the elements that release more energy upon an electron gain are
a.
$Cl, Se$ and $Na$
b.
$Cl, S$ and $Li$
c.
$F, S$ and $Li$
d.
$F, Se$ and $Na$
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Q49 nat
$3\,g$ of acetic acid is added to $250\,mL$ of $0.1\,M\,HCl$ and the solution made up to $500\,mL$ . To $20\,mL$ of this solution $\frac{1}{2\,}mL$ of $5M\,NaOH$ is added. The $pH$ of the solution is ________ [Given: $pKa$ of acetic acid $= 4.75,$ molar mass of acetic acid $60\,g/mol, log 3 = 0.4771$ , Neglect any changes in volume]
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Q50 mcq
A chromatography column, packed with silica gel as stationary phase, was used to separate a mixture of compounds consisting of $(A)$ benzanilide $(B)$ aniline and $(C)$ acetophenone. When the column is eluted with a mixture of solvents, hexane:ethyl acetate $(20 : 80)$ , the sequence of obtained compounds is:
a.
$(B), (C)$ and $(A)$
b.
$(B), (A)$ and $(C)$
c.
$(C), (A)$ and $(B)$
d.
$(A), (B)$ and $(C)$
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Q51 mcq
If the sum of the first $40$ terms of the series, $3 + 4 + 8 + 9 + 13 + 14 + 18 + 19+. . . .$ is $(102)m,$ then $m$ is equal to
a.
$20$
b.
$25$
c.
$5$
d.
$10$
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Q52 nat
$|$ If the system of linear equations, $x+y+z= 6$ $x+ 2y+ 3z= 10$ $3x+ 2y+\lambda z=\mu$ has more than two solutions, then $\mu - \lambda ^{2}$ , is equal to.
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Q53 mcq
The coefficient of $x^{7}$ in the expression $(1 +x)^{10} +x(1 +x)^{9} +x^{2}(1 +x)^{8}+. . . . +x^{10}$ , is
a.
$210$
b.
$330$
c.
$120$
d.
$420$
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Q54 mcq
The locus of the mid-points of the perpendiculars drawn from points on the line $x= 2y$ , to the line $x=y$ , is.
a.
$2x-3y= 0$
b.
$5x-7y= 0$
c.
$3x-2y= 0$
d.
$7x-5y= 0$
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Q55 mcq
The value of $c$ , in the Lagrange’s mean value theorem for the function $f(x) =x^{3} -4x^{2} + 8x+ 11,$ when $x\in [0,1]$ , is
a.
$\frac{4-\sqrt{5}}{3}$
b.
$\frac{4-\sqrt{7}}{3}$
c.
$\frac{2}{3}$
d.
$\frac{\sqrt{7}-2}{3}$
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Q56 mcq
Let $y=y(x)$ be a function of $x$ satisfying $y\sqrt{1 -x^{2}} =k- x\sqrt{1 -y^{2}}$ where $k$ is a constant and $y(\frac{1}{2} )= -\frac{1}{4}$ .Then $\frac{dy}{dx}$ at $x= \frac{1}{2}$ , is equal to
a.
$-\frac{\sqrt{5}}{4}$
b.
$-\frac{\sqrt{5}}{2}$
c.
$\frac{2}{\sqrt{5}}$
d.
$\frac{\sqrt{5}}{2}$
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Q57 mcq
Let $A,B,C$ and $D$ be four non-empty sets. The contrapositive statement of “If $A⊆ B$ and $B⊆ D$ , then $A⊆ C$ ” is
a.
If $A⊈ C$ , then $A⊆ B$ and $B⊆ D$
b.
If $A⊆ C$ , then $B\subset A$ and $D\subset B$
c.
If $A⊈ C$ , then $A⊈ B$ and $B⊆ D$
d.
If $A⊈ C$ , then $A⊈ B$ or $B⊈ D$
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Q58 mcq
If $\theta _{1}$ and $\theta _{2}$ be respectively the smallest and the largest values of $\theta$ in $(0, 2\pi ) -{\pi }$ which satisfy the equation, $2cot^{2}\theta - \frac{5}{sin\theta} + 4 = 0$ , then $\int ^{\theta _{2}} cos^{2}3\theta d\theta$ is equal to: $\theta _{1}$
a.
$\frac{\pi}{3}$
b.
$\frac{2\pi}{3}$
c.
$\frac{\pi}{3} + \frac{1}{6}$
d.
$\frac{\pi}{9}$
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Q59 nat
$\frac{1}{x}log_{e}(\frac{1+3x}{1-2x}), when\,x\neq 0$ If the function $f$ defined on $(-\frac{1}{3}, 1/3)$ by $f(x) ={$ , is continuous, then $k$ is $k , when\,x= 0$ equal to.
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Q60 nat
If the foot of the perpendicular drawn from the point $(1, 0, 3)$ on a line passing through $(\alpha , 7,1)$ is $(\frac{5}{3} , \frac{7}{3}, \frac{17}{3} )$ , then $\alpha$ is equal to
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Q61 mcq
If $3x+ 4y= 12\sqrt{2}$ is a tangent o the ellipse $\frac{x^{2}}{a^{2}} + \frac{y^{2}}{9} = 1$ for some $a\in R,$ then the distance between the foci of the ellipse is
a.
$2\sqrt{7}$
b.
$4$
c.
$2\sqrt{5}$
d.
$2\sqrt{2}$
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Q62 mcq
Let $a_{1},a_{2},a_{3}, …$ , be a $G. P.$ such that $a_{1} < 0,a_{1}+a_{2} = 4$ and $a_{3}+a_{4} = 16$ . If $\sum ^{9}_{i=1} a_{i} = 4\lambda$ , then $\lambda$ , is equal to.
a.
$-513$
b.
$-171$
c.
$171$
d.
$\frac{511}{3}$
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Q63 mcq
In a workshop, there are five machines and the probability of any one of them to be out of service on a day is $\frac{1}{4}$ . If the probability that at most two machines will be out of service on the same day is $(\frac{3}{4} )^{3}k,$ then $k$ is equal to
a.
$\frac{17}{8}$
b.
$\frac{17}{4}$
c.
$\frac{17}{2}$
d.
$4$
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Q64 mcq
Let $\alpha$ and $\beta$ be the roots of the equation $x^{2} - x-1 = 0$ . If $p_{k} = (\alpha )^{k} + (\beta )^{k},k\geq 1,$ then which one of the following statements is not true?
a.
$p_{3} =p_{5}- p_{4}$
b.
$p_{5} = 11$
c.
$(p_{1}+p_{2}+p_{3}+p_{4}+p_{5}) = 26$
d.
$p_{5} =p_{2}\cdot p_{3}$
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Q65 nat
Let $X = {n\in N : 1 \leq n\leq 50}$ . If $A= {n\in X : \,n\,is\,a\,multiple\,of\,2}$ and $B = {n\in X : \,n\,is\,a\,multiple\,of\,7}$ , then the number of elements in the smallest subset of $X$ , containing both $A$ and $B$ , is.
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Q66 mcq
Let the tangents drawn from the origin to the circle, $x^{2} +y^{2} -8x-4y+ 16 = 0$ touch it at the points $A$ and $B$ . Then $(AB)^{2}$ is equal to
a.
$\frac{52}{5}$
b.
$\frac{56}{5}$
c.
$\frac{64}{5}$
d.
$\frac{32}{5}$
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Q67 mcq
If $\frac{3+isin\theta}{4-icos\theta},\theta \in [0 ,2\pi ],$ is a real number, then an argument of $sin\theta +icos\theta$ is
a.
$\pi -tan^{-1}(\frac{4}{3})$
b.
$\pi -tan^{-1}(\frac{3}{4})$
c.
$-tan^{-1}(\frac{3}{4})$
d.
$tan^{-1}(\frac{4}{3})$
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Q68 nat
If the mean and variance of eight numbers $3, 7, 9, 12, 13, 20,x$ and $y$ be $10$ and $25$ respectively, then $x\cdot y$ is equal to
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Q69 mcq
Let $y=y(x)$ be the solution curve of the differential equation, $(y^{2} - x)\frac{dy}{dx} = 1$ , satisfying $y(0) = 1$ . This curve intersects the $X-$ axis at a point whose abscissa is
a.
$2 - e$
b.
$-e$
c.
$2$
d.
$2 +e$
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Q70 mcq
Let $A = [a_{ij}]$ and $B = [b_{ij}]$ be two $3 \times 3$ real matrices such that $b_{ij} = (3)^{(i+j-2)}a_{ij}$ , where $i,j= 1,2, 3$ . If the determinant of $B$ is $81$ , then determinant of $A$ is
a.
$\frac{1}{3}$
b.
$3$
c.
$\frac{1}{81}$
d.
$\frac{1}{9}$
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Q71 mcq
Let $f(x)$ be a polynomial of degree $5$ such that $x= \pm 1$ are its critical points. If $_{x}lim_{\rightarrow 0\rightarrow } (2 + \frac{f(x)}{x^{3}})= 4,$ then which one of the following is not true?
a.
$f$ is an odd function
b.
$f(1) -4f(-1) = 4$ . $x= 1$ is a point of maximum and $x= -1$
c.
$x= 1$ is a point of local minimum and $x= -1$ is a point of local maximum
d.
$x= 1$ is a point of local maxima of $f$
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Q72 mcq
$\rightarrow \rightarrow$ Let $\vec{a}, \vec{b}$ and $\vec{c}$ , be three unit vectors such that $\vec{a}+ \vec{b}+ \vec{c}= 0$ . If $\lambda = \vec{a}\cdot \vec{b}+ \vec{b}\cdot \vec{c}+ \vec{c}\cdot \vec{a}$ and $\vec{d}= \vec{a}\times \vec{b}+ \vec{b}\times \vec{c}+ \vec{c}\times \vec{a}$ , then the order pair, $(\lambda , \vec{d})$ , is equal to.
a.
$( \frac{3}{2}, 3\vec{a}\times \vec{c})$
b.
$(-\frac{3}{2}, 3\vec{c}\times \vec{b})$
c.
$(\frac{3}{2}, 3\vec{b}\times \vec{c})$
d.
$(-\frac{3}{2}, 3\vec{a}\times \vec{b})$
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Q73 mcq
The number of ordered pairs $(r,k)$ for which $6.^{35}C_{r} =(k^{2} -3).^{36}C_{r+1},$ where $k$ is an integer is
a.
$3$
b.
$2$
c.
$6$
d.
$4$
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Q74 mcq
The area (in sq. units) of the region ${(x,y) \in R^{2} 4x^{2} \leq y\leq 8x+ 12}$ is
a.
$\frac{125}{3}$
b.
$\frac{128}{3}$
c.
$\frac{124}{3}$
d.
$\frac{127}{3}$
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Q75 mcq
$2$ The value of $\alpha$ for which $4\alpha \int e^{-\alpha |x|}dx= 5$ , is $-1$
a.
$log_{e}2$
b.
$log_{e}(\frac{3}{2})$
c.
$log_{e} \sqrt{2}$
d.
$log_{e}(\frac{4}{3})$
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