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JEE Main 2020 (08 Jan Shift 2)

2020 · 75 questions · First 10 Solutions Free
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Q1 mcq
In a double - slit experiment, at a certain point on the screen the path difference between the two interfering waves is $\frac{1}{8}th$ of a wavelength. The ratio of the intensity of light at that point to that at the center of a bright fringe is:
a.
$0.853$ Correct Answer
b.
$0.672$
c.
$0.568$
d.
$0.760$

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Q2 mcq
A capacitor is made of two square plates each of side ‘ $a$ ’ making a very small angle $\alpha$ between them, as shown in figure. The capacitance will be close to:
Question 2 image
a.
$\frac{\in _{0}a^{2}}{d}(1 - \frac{\alpha a}{2d})$ Correct Answer
b.
$\frac{\in _{0}a^{2}}{d}(1 - \frac{\alpha a}{4d})$
c.
$\frac{\in _{0}a^{2}}{d}(1 + \frac{\alpha a}{d})$
d.
$\frac{\in _{0}a^{2}}{d}(1 - \frac{3\alpha a}{2d} )$

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Q3 mcq
A very long wire ABDMNDC is shown in figure carrying current I. AB and BC parts are straight, long and at right angle. At D wire forms a circular turn DMND of radius R. AB, BC parts are tangential to circular turn at N and D. Magnetic filed at the center of circle is:
Question 3 image
a.
$\frac{\mu _{0}I}{2\pi R} (\pi + \frac{1}{\sqrt{2}} )$ Correct Answer
b.
$\frac{\mu _{0}I}{2\pi R}(\pi - \frac{1}{\sqrt{2}})$
c.
$\frac{\mu _{0}I}{2\pi R} (\pi + 1)$
d.
$\frac{\mu _{0}I}{2R}$

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Q4 mcq
A transverse wave travels on a taut steel wire with a velocity of $v$ when tension in it is $2.06 \times 10^{4}N.$ When the tension is changed to $T,$ the velocity changed to $\frac{v}{2}.$ The value of $T$ is close to:
a.
$2.50 \times 10^{4}N$
b.
$5.15 \times 10^{3} N$ Correct Answer
c.
$30.5 \times 10^{4} N$
d.
$10.2 \times 10^{2} N$

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Q5 nat
The first member of the Balmer series of hydrogen atom has a wavelength of $6561\,A^{\circ }$ . The wavelength of the second member of the Balmer series (in nm) is_____________
✓ Accepted Answer: 486

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Q6 mcq
A galvanometer having a coil resistance $100 \Omega$ gives a full scale deflection when a current of $1mA$ is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter given full scale deflection for a potential difference of $10V?$
a.
$10k\Omega$
b.
$8.9 k\Omega$
c.
$7.9 k\Omega$
d.
$9.9 k\Omega$ Correct Answer

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Q7 mcq
A uniform sphere of mass $500\,g$ rolls without slipping on a plane horizontal surface with its centre moving at a speed of $5.00\, cm \,s^{-1}$ . Its kinetic energy is:
a.
$8.75 \times 10^{-4} J$ Correct Answer
b.
$8.75 \times 10^{-3} J$
c.
$6.25 \times 10^{-4} J$
d.
$1.13 \times 10^{-3} J$

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Q8 mcq
An electron (mass $m$ ) with initial velocity $\vec{v}=v_{0}ˆi+v_{0}ˆj$ is in an electric filed $\vec{E} = -E_{0}ˆk.$ If $\lambda _{0}$ is initial de- Broglie wavelength of electron, its de-Broglie wave length at time $t$ is given by:
a.
$\frac{\lambda _{0}\sqrt{2}}{2E2t2}$ $\sqrt{1}+^{e}_{m2v20}$
b.
$\frac{\lambda _{0}}{e2E2t2}$ $\sqrt{1}+_{m2v20}$
c.
$\frac{\lambda _{0}}{e2E2t2}$ $\sqrt{1}+_{2m2v20}$ Correct Answer
d.
$\frac{\lambda _{0}}{e2E2t2}$ $\sqrt{2}+_{m2v20}$

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Q9 mcq
A particle of mass $m$ is dropped from a height $h$ above the ground. At the same time another particle of the same mass is thrown vertically upwards from the ground with a speed of $\sqrt{2gh}.$ If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of $\sqrt{\frac{h}{g}}$ is:
a.
$\sqrt{\frac{1}{2}}$
b.
$\sqrt{\frac{3}{4}}$
c.
$\frac{1}{2}$
d.
$\sqrt{\frac{3}{2}}$ Correct Answer

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Q10 mcq
In the given circuit, value of $Y$ is:
Question 10 image
a.
$0$ Correct Answer
b.
toggles between $0$ and $1$
c.
will not execute
d.
$1$

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Q11 mcq
An object is gradually moving away from the focal point of a concave mirror along the axis of the mirror. The graphical representation of the magnitude of linear magnification $(m)$ versus distance of the object from the mirror $(x)$ is correctly given by (Graphs are drawn schematically and are not to scale)
Question 11 image
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Q12 mcq
Two liquids of densities $\rho _{1}$ and $\rho _{2}(\rho _{2} = 2\rho _{1})$ are filled up behind a square wall of side $10m$ as shown in figure. Each liquid has a height of $5m.$ The ratio of the forces due to these liquids exerted on upper part MN to that at the lower part NO is (Assume that the liquids are not mixing):
a.
$\frac{1}{3}$
b.
$\frac{2}{3}$
c.
$\frac{1}{2}$
d.
$\frac{1}{4}$
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Q13 mcq
A particle of mass $m$ and charge $q$ is released from rest in a uniform electric field. If there is no other force on the particle, the dependence of its speed $v$ on the distance $x$ travelled by it is correctly given by (graphs are schematic and not drawn to scale)
Question 13 image
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Q14 mcq
A particle moves such that its position vector $\vec{r}(t) = cos\omega tˆi+ sin\omega tˆj$ where $\omega$ is a constant and $t$ is time. Then which of the following statements is true for the velocity $\vec{v}(t)$ and acceleration $\vec{a}(t)$ of the particle:
a.
$\vec{v}$ is perpendicular to $\vec{r}$ and $\vec{a}$ is directed away from the origin
b.
$\vec{v}$ and $\vec{a}$ both are perpendicular to $\vec{r}$
c.
$\vec{v}$ and $\vec{a}$ both are parallel to $\vec{r}$
d.
$\vec{v}$ is perpendicular to $\vec{r}$ and $\vec{a}$ is directed towards the origin
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Q15 mcq
A Carnot engine having an efficiency of $\frac{1}{10}$ is being used as a refrigerator. If the work done on the refrigerator is $10\,J,$ the amount of heat absorbed from the reservoir at a lower temperature is
a.
$99\,J$
b.
$100\,J$
c.
$1\,J$
d.
$90\,J$
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Q16 mcq
As shown in figure. When a spherical cavity (centred at $O$ ) of radius $1$ is cut out of a uniform sphere of radius $R$ (centred at $C$ ), the centre of mass of remaining (shaded part of sphere is at $G,$ i.e., on the surface of the cavity. $R$ can be determined by the equation:
Question 16 image
a.
$(R^{2} +R+ 1)(2 - R) = 1$
b.
$(R^{2} - R-1)(2 - R) = 1$
c.
$(R^{2} - R+ 1)(2 - R) = 1$
d.
$(R^{2} +R-1)(2 - R) = 1$
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Q17 mcq
A plane electromagnetic wave of frequency $25GHz$ is propagating in vacuum along the z-direction. At a particular point in space and time, the magnetic filed is given by $^{-8}ˆ$ The corresponding electric $\vec{B}= 5 \times 10 j T.$ field $\vec{E}$ is (speed of light $= 3 \times 10^{8} m\,s^{-1}$ )
a.
$1.66 \times 10^{-16}ˆi \frac{V}{m}$
b.
$-1.66 \times 10^{-16}ˆi \frac{V}{m}$
c.
$-15ˆi\frac{V}{m}$
d.
$15ˆi\frac{V}{m}$
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Q18 mcq
A simple pendulum is being used to determine the value of gravitational acceleration $g$ at a certain place. The length of the pendulum is $25.0\,cm$ and a stopwatch with $1\,s$ resolution measures the time taken for $40$ oscillations to be $50\,s$ . The accuracy in $g$ is:
a.
$5.40%$
b.
$3.40%$
c.
$4.40%$
d.
$2.40%$
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Q19 nat
An asteroid is moving directly towards the centre of the earth. When at a distance of $10R$ ( $R$ is the radius of the earth) from the centre of the earth, it has a speed of $12\, km \,s^{-1}.$ Neglecting the effect of earth's atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is $11.2\,km\,s^{-1})$ ? Give your answer to the nearest integer in $km \,s^{-1}$ __________.
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Q20 nat
The series combination of two batteries, both of the same emf $10V,$ but different internal resistance of $20 \Omega$ and $5 \Omega ,$ is connected to the parallel combination of two resistors $30 \Omega$ and $x \Omega .$ The voltage difference across the battery of internal resistance $20 \Omega$ is zero, the value of $x$ (in $\Omega )$ is____
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Q21 mcq
Consider a mixture of $n$ moles of helium gas and $2n$ moles of oxygen gas (molecules taken to be rigid) as an ideal gas. Its $\frac{C_{P}}{C_{V}}$ value will be:
a.
$\frac{19}{13}$
b.
$\frac{67}{45}$
c.
$\frac{40}{27}$
d.
$\frac{23}{15}$
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Q22 mcq
As shown in the figure, a battery of emf $\in$ is connected to an inductor $L$ and resistance $R$ in series. The switch is closed at $t= 0.$ The total charge that flows from the battery, between $t= 0$ and $t=t_{c}$ ( $t_{c}$ is the time constant of the circuit) is:
a.
$\frac{\in L}{eR^{2}}$
b.
$\frac{\in L}{R^{2}}(1 - \frac{1}{e})$
c.
$\frac{\in L}{R^{2}}$
d.
$\frac{\in R}{eL^{2}}$
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Q23 nat
Three containers $C_{1},C_{2}$ and $C_{3}$ have water at different temperatures. The table below shows the final temperature $T$ when different amounts of water (given in liters) are taken from each container and mixed (assume no loss of heat during the process) $C_{1} C_{2} C_{3} T$ $1l 2l -- 60^{o}C$ $-- 1l 2l 30^{o}C$ $2l -- 1l 60^{o}C$ $1l 1l 1l \theta$ The value of $\theta$ (in $^{o}C$ to the nearest integer) is___________
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Q24 mcq
Consider two charged metallic spheres $S_{1}$ and $S_{2}$ of radii $R_{1}$ and $R_{2},$ respectively. The electric fields $E_{1}$ (on $S_{1}$ ) and $E_{2}$ (on $S_{2}$ ) on their surfaces are such that $\frac{E_{1}}{E_{2}} = \frac{R_{1}}{R_{2}} .$ Then the ratio $V_{1}$ (on $S_{1}$ ) $/V_{2}$ (on $S_{2}$ ) of the electrostatic potentials on each sphere is:
a.
$\frac{R}{R_{2}}^{1}$
b.
$2$ $(\frac{R_{1}}{R_{2}})$
c.
$(\frac{R_{2}}{R_{1}})$
d.
$3$ $(\frac{R_{1}}{R_{2}})$
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Q25 nat
A ball is dropped from the top of a $100\,m$ high tower on a planet. In the last $\frac{1}{2}s$ before hitting the ground, it covers a distance of $19\,m.$ Acceleration due to gravity (in $m\,s^{-2}$ ) near the surface on that planet is______
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Q26 mcq
The increasing order of the atomic radii of the following elements is: $(a)C$ $(b)O$ $(c)F$ $(d)Cl$ $(e)Br$
a.
$(b) < (c) < (d) < (a) < (e)$
b.
$(d) < (c) < (b) < (a) < (e)$
c.
$(c) < (b) < (a) < (d) < (e)$
d.
$(a) < (b) < (c) < (d) < (e)$
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Q27 mcq
The correct order of the calculated spin-only magnetic moments of complexes $(A)$ to $(D)$ is: $(A)Ni(CO)_{4}$ $(B) [Ni(H_{2}O)_{6}]Cl_{2}$ $(C)Na_{2}[Ni(CN)_{4}]$ $(D)PdCl_{2}(PPh_{3})_{2}$
a.
$(A) ≈(C) < (B) ≈(D)$
b.
$(C) < (D) < (B) < (A)$
c.
$(C) ≈(D) < (B) < (A)$
d.
$(A) ≈(C) ≈(D) < (B)$
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Q28 mcq
The major product $[B]$ in the following sequence of reactions is:
Question 28 image
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Q29 mcq
Among the reactions $(a) -(d),$ the reaction(s) that does/do not occur in the blast furnace during the extraction of iron is/are: $(a)CaO+SiO_{2} \rightarrow \rightarrow CaSiO_{3}$ $(b) 3Fe_{2}O_{3}+CO\rightarrow 2\rightarrow Fe_{3}O_{4}+CO_{2}$ $(c)FeO+SiO_{2} \rightarrow \rightarrow FeSiO_{3}$ $(d)FeO Fe+ \frac{1}{2} O_{2}$
a.
$a$
b.
$a$ and $d$
c.
$c$ and $\vec{d}$
d.
$d$
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Q30 mcq
Arrange the following bonds according to their average bond energies in descending order: $C -Cl, C -Br, C -F, C -I$
a.
$C- F >C- Cl>C- Br>C- I$
b.
$C- Br>C- I >C- Cl>C- F$
c.
$C- I >C- Br>C- Cl>C- F$
d.
$C- Cl>C- Br>C- I >C- F$
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Q31 nat
$2+$ For an electrochemical cell $Sn(s) Sn^{2} + (aq, 1M) Pb^{2+}(aq, 1M) Pb(s)$ the ratio $\frac{[Sn]}{[Pb^{2+}]}$ when this cell attains equilibrium is _______ (Given: $E^{0}_{Sn^{2+}}_{Sn} = -0 .14 V, E^{0}_{Pb^{2+}}_{Pb} = -0 .13 V, \frac{2.303RT}{F} = 0 .06$ )
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Q32 mcq
Among the compounds $A$ and $B$ with molecular formula $C_{9}H_{18}O_{3}, A$ is having higher boiling point than $B.$ The possible structures of $A$ and $B$ are:
Question 32 image
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Q33 mcq
A metal $(A)$ on heating in nitrogen gas gives compound $B.$ on treatment with $B H_{2}O$ gives a colourless gas which when passed through $CuSO_{4}$ solution gives a dark blue-violet coloured solution. $A$ and $B$ respectively, are:
a.
$Na$ and $NaNO_{3}$
b.
$Na$ and $Mg_{3}N_{2}$
c.
$Mg$ and $Mg_{3}N_{2}$
d.
$Mg$ and $Mg(NO_{3})_{2}$
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Q34 nat
In the following sequence of reactions the maximum number of atoms present in molecule ‘ $C$ ’ in one plane is_______ $--A^{Red}_{Cu tu}^{hot}_{\vec{b}e} B_{Anhydrous A}^{CH_{3}Cl(1.eq)}_{\vec{l}Cl_{3}} C$ (A is a lowest molecular weight alkyne)
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Q35 mcq
Preparation of Bakelite proceeds via reactions:
a.
Electrophilic addition and dehydration
b.
Condensation and elimination
c.
Electrophilic substitution and dehydration
d.
Nucleophilic addition and dehydration
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Q36 mcq
Among $(a) -(d),$ the complexes that can show geometrical isomerism are: $(a) [Pt(NH_{3})_{3}Cl]^{+}$ $(b) [Pt(NH_{3})Cl_{5}]^{-}$ $(c) [Pt(NH_{3})_{2}Cl(NO_{2})]$ $(d) [Pt(NH_{3})_{4}ClBr]^{2+}$
a.
$b$ and $c$
b.
$d$ and $a$
c.
$c$ and $d$
d.
$a$ and $b$
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Q37 mcq
Two monomers in maltose are:
a.
$\alpha - D-$ glucose and $\beta - D-$ glucose
b.
$\alpha - D-$ glucose and $\alpha - D-$ galactose
c.
$\alpha - D-$ glucose and $\alpha - D-$ Fructose
d.
$\alpha - D-$ glucose and $\alpha - D-$ glucose
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Q38 mcq
Hydrogen has three isotopes $(A), \,(B)$ and $(C).$ If the number of neutron(s) in $(A), \,(B)$ and $(C)$ respectively, are $(x), \,(y)$ and $(z),$ the sum of $(x), \,(y)$ and $(z)$ is
a.
$3$
b.
$2$
c.
$4$
d.
$1$
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Q39 mcq
An unsaturated hydrocarbon $X$ absorbs two hydrogen molecules on catalytic hydrogenation, and also gives following reaction: $--X^{(i)O_{3}} A^{[Ag (NH_{3})}\rightarrow \rightarrow^{_{2}]^{+}} B^{(3-oxo-hexanedicarboxylic acid)}X^{will be:}$ $\frac{(ii)\vec{Z}n}{H2O}$
Question 39 image
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Q40 mcq
For the following Assertion and Reason, the correct option is: Assertion: The $pH$ of water increases with increase in temperature. Reason: The dissociation of water into $H^{+}$ and $OH^{-}$ is an exothermic reaction.
a.
Both assertion and reason are true, and the reason is the correct explanation for the assertion.
b.
Both assertion and reason are false.
c.
Both assertion and reason are true, but the reason is not the correct explanation for the assertion.
d.
Assertion is not true, but reason is true.
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Q41 mcq
The major product in the following reaction is:
Question 41 image
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Q42 mcq
White phosphorus on reaction with concentrated $NaOH$ solution in an inert atmosphere of $CO_{2}$ gives phosphine and compound $(X). (X)$ on acidification with $HCl$ gives compound $(Y).$ The basicity of compound $(Y)$ is:
a.
$2$
b.
$1$
c.
$4$
d.
$3$
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Q43 nat
Complexes $(ML_{5})$ of metals $Ni$ and $Fe$ have ideal square pyramidal and trigonal bipyramidal geometries, respectively. The sum of the $90^{o}, 120^{o}$ and $180^{o} L -M -L$ angles in the two complexes is_______
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Q44 mcq
Kjeldahl’s method cannot be used to estimate nitrogen for which of the following compounds?
Question 44 image
a.
$C_{6}H_{5}NH_{2}$
b.
$CH_{3}CH_{2}-C \equiv N$
c.
$C_{6}H_{5}NO_{2}$
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Q45 mcq
The radius of the second Bohr orbit, in terms of the Bohr radius, $a_{0},$ in $Li^{2+}$ is:
a.
$\frac{2a_{0}}{3}$
b.
$\frac{4a_{0}}{9}$
c.
$\frac{4a_{0}}{3}$
d.
$\frac{2a_{0}}{9}$
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Q46 mcq
For the following Assertion and Reason, the correct option is: Assertion: For hydrogenation reactions, the catalytic activity increases from Group $5$ to Group $11$ metals with maximum activity shown by Group $7 -9$ elements. Reason: The reactants are most strongly adsorbed on group $7 -9$ elements.
a.
The assertion is true, but the reason is false
b.
Both assertion and reason are false
c.
Both assertion and reason are true and the reason is the correct explanation for the assertion
d.
Both assertion and reason are true but the reason is not the correct explanation for the assertion
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Q47 mcq
Consider the following plots of rate constant versus $\frac{1}{T}$ for four different reactions. Which of the following orders is correct for the activation energies of these reactions?
Question 47 image
a.
$E_{b} >E_{a} >E_{d} >E_{c}$
b.
$E_{a} >E_{c} >E_{d} >E_{b}$
c.
$E_{c} >E_{a} >E_{d} >E_{b}$
d.
$E_{b} >E_{d} >E_{c} >E_{a}$
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Q48 mcq
Which of the following compounds is likely to show both Frenkel and Schottky defects in its crystalline form?
a.
$AgBr$
b.
$CsCl$
c.
$KBr$
d.
$ZnS$
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Q49 nat
$NaClO_{3}$ is used, even in spacecrafts, to produce $O_{2}.$ The daily consumption of pure $O_{2}$ by a person in $492\,L$ at $1$ atm, $300K.$ How much amount of $NaClO_{3},$ in grams, is required to produce $O_{2}$ for the daily consumption of a person at $1$ atm, $300K$ ? _____ $NaClO_{3}(s) + Fe(s) O_{2}(g) + NaCl(s) + FeO(s)$ $R = 0 .082 \,L\, atm \, \vec{m}ol^{-1} \,K^{-1}$
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Q50 nat
At constant volume, $4\,mol$ of an ideal gas when heated from $300K$ to $500K$ changes its internal energy by $5000J.$ The molar heat capacity at constant volume is ________
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Q51 mcq
Let $\alpha = \frac{-1+i\sqrt{3}}{2}$ . If $a= (1 +\alpha )\sum ^{100}_{k=0} \alpha ^{2k}$ and $b=\sum ^{100}_{k=0} \alpha ^{3k}$ , then $a$ and $b$ , are the roots of the quadratic equation.
a.
$x^{2} + 101x+ 100 = 0$
b.
$x^{2} -102x+ 101 = 0$
c.
$x^{2} -101x+ 100 = 0$
d.
$x^{2} + 102x+ 101 = 0$
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Q52 mcq
If the $10^{th}$ , term of an A.P. is $\frac{1}{20}$ , and its $20^{th}$ , term is $\frac{1}{10}$ , then the sum of its first $200$ , terms is.
a.
$50$
b.
$50\frac{1}{4}$
c.
$100$
d.
$100\frac{1}{2}$
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Q53 mcq
The differential equation of the family of curves, $x^{2} = 4b(y+b), \,b\in R$ , is.
a.
$x(y')^{2} =x+ 2yy'$
b.
$x(y')^{2} = 2yy' - x$
c.
$xy'' =y'$
d.
$x(y')^{2} =x-2yy'$
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Q54 mcq
The system of linear equations $\lambda x+ 2y+ 2z= 5$ $2\lambda x+ 3y+ 5z= 8$ $4x+\lambda y+ 6z= 10$ has
a.
no solution when $\lambda = 8$
b.
a unique solution when $\lambda = -8$
c.
no solution when $\lambda = 2$
d.
infinitely many solutions when $\lambda = 2$
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Q55 nat
The number of $4$ letter words (with or without meaning) that can be formed from the eleven letters of the word $EXAMINATION$ is
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Q56 mcq
If a hyperbola passes through the point $P(10, 16)$ , and it has vertices at $(\pm 6, 0)$ , then the equation of the normal to it at $P$ , is.
a.
$3x+ 4y= 94$
b.
$2x+ 5y= 100$
c.
$x+ 2y= 42$
d.
$x+ 3y= 58$
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Q57 mcq
The mirror image of the point $(1, 2, 3)$ , in a plane is $(- \frac{7}{3}, -\frac{4}{3}, -\frac{1}{3} ).$ Which of the following points lies on this plane?
a.
$(1, \,1, \,1)$
b.
$(1, -1, \,1)$
c.
$(-1, -1, \,1)$
d.
$(-1, -1, -1)$
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Q58 mcq
Let $S$ , be the set of all functions $f : [0, 1] \rightarrow \rightarrow R$ , which are continuous on $[0, 1]$ , and differentiable on $(0, 1)$ . Then for every $f$ in $S$ , there exists $c\in (0, 1)$ , depending on $f$ , such that.
a.
$|f(c) - f(1)| < (1 - c) f'(c)$
b.
$\frac{f(1)-f(c)}{1-c} =f'(c)$
c.
$|f(c) +f(1)| < (1 +c) f'(c)$
d.
$|f(c) - f(1)| < f'(c)$
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Q59 mcq
Let $S$ , be the set of all real roots of the equation, $3^{x}(3^{x} -1) + 2 = |3^{x} -1| + |3^{x} -2|$ , then
a.
contains exactly two elements.
b.
is a singleton.
c.
is an empty set.
d.
contains at least four elements.
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Q60 mcq
Let $f : (1, 3) \rightarrow \rightarrow R$ , be a function defined by $f(x) = \frac{x[x]}{1+x^{2}},$ where $[x]$ , denotes the greatest integer $\leq x.$ Then the range of $f$ , is
a.
$(\frac{2}{5} , \frac{3}{5}]\cup (\frac{3}{4} , \frac{4}{5})$
b.
$(\frac{2}{5}, \frac{1}{2})\cup (\frac{3}{5} , \frac{4}{5} ]$
c.
$(\frac{2}{5} , \frac{4}{5}]$
d.
$(\frac{3}{5}, \frac{4}{5})$
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Q61 mcq
Let $\vec{a}= ˆi-2ˆj+ˆk$ and $\vec{b}= ˆi- ˆj+ ˆk$ , be two vectors. If $\vec{c}$ , is a vector such that $\vec{b}\times \vec{c}= \vec{b}\times \vec{a}$ and $\vec{c}\cdot \vec{a}= 0,$ then $\vec{c}\cdot \vec{b}$ , is equal to.
a.
$-\frac{3}{2}$
b.
$\frac{1}{2}$
c.
$-\frac{1}{2}$
d.
$-1$
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Q62 nat
If $\frac{\sqrt{2}sin\alpha}{\sqrt{1+cos2\alpha}} = \frac{1}{7}$ and $\sqrt{\frac{1-cos2\beta}{2}} = \frac{1}{\sqrt{10}}, \,\alpha , \beta \in (0, \frac{\pi}{2})$ , then $tan(\alpha + 2\beta )$ , is equal to
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Q63 mcq
The length of the perpendicular from the origin, on normal to the curve, $x^{2} + 2xy-3y^{2} = 0$ , at the point $(2, 2)$ , is.
a.
$\sqrt{2}$
b.
$4\sqrt{2}$
c.
$2$
d.
$2\sqrt{2}$
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Q64 mcq
$_{x}lim_{\rightarrow 0\rightarrow } \frac{\int _{0}^{x}tsin(10t)dt}{x}$ , is equal to
a.
$0$
b.
$\frac{1}{10}$
c.
$-\frac{1}{5}$
d.
$- \frac{1}{10}$
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Q65 mcq
$2$ If $I = \int \frac{dx}{\sqrt{2x^{3}-9x^{2}+12x+4}}$ , then $1$
a.
$\frac{1}{8} <I^{2} < \frac{1}{4}$
b.
$\frac{1}{9} <I^{2} < \frac{1}{8}$
c.
$\frac{1}{16} <I^{2} < \frac{1}{9}$
d.
$\frac{1}{6} <I^{2} < \frac{1}{2}$
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Q66 mcq
$2 2 1 0$ If $A=( )$ and $I =( ),$ then $10A^{-1}$ , is equal to. $9 4 0 1$
a.
$A-4I$
b.
$6I- A$
c.
$A-6I$
d.
$4I- A$
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Q67 mcq
The mean and variance of $20$ observations are found to be $10$ and $4,$ respectively. On rechecking, it was found that an observation $9$ was incorrect and the correct observation was $11,$ then the correct variance is
a.
$3.99$
b.
$4.01$
c.
$4.02$
d.
$3.98$
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Q68 mcq
If a line $y=mx+c$ , is a tangent to the circle $(x-3)^{2} +y^{2} = 1$ , and it is perpendicular to a line $L_{1},$ where $L_{1}$ is the tangent to the circle $x^{2} +y^{2} = 1$ , at the point $(\frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}})$ , then
a.
$c^{2} -7c+ 6 = 0$
b.
$c^{2} + 7c+ 6 = 0$
c.
$c^{2} + 6c+ 7 = 0$
d.
$c^{2} -6c+ 7 = 0$
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Q69 mcq
If $\alpha$ and $\beta$ , be the coefficients of $x^{4}$ and $x^{2}$ , respectively in the expansion of $(x+ \sqrt{x^{2}-1})^{6} +(x- \sqrt{x^{2}-1})^{6}$ , then
a.
$\alpha +\beta = 60$
b.
$\alpha +\beta = -30$
c.
$\alpha - \beta = 60$
d.
$\alpha - \beta = -132$
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Q70 mcq
$||$ $|| ||$ The area (in sq. units) of the region ${(x, y) \in R^{2} :x^{2} \leq y\leq 3 -2x}$ , is.
a.
$\frac{32}{3}$
b.
$\frac{34}{3}$
c.
$\frac{29}{3}$
d.
$\frac{31}{3}$
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Q71 mcq
$|||$ $||$ Which of the following statement is a tautology?
a.
$p\vee (~q) \rightarrow \rightarrow p\wedge q$
b.
$~(p\wedge ~q) \rightarrow \rightarrow p\vee q$
c.
$~(p\vee ~q) \rightarrow \rightarrow p\wedge q$
d.
$~(p\vee ~q) \rightarrow \rightarrow p\vee q$
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Q72 nat
Let $f(x)$ , be a polynomial of degree $3$ , such that $f(-1) = 10, f(1) = -6, f(x)$ , has a critical point at $x= -1$ and $f'(x)$ , has a critical point at $x= 1.$ Then $f(x)$ , has local minima at $x=$
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Q73 mcq
Let $A$ and $B$ , be two events such that the probability that exactly one of them occurs is $\frac{2}{5}$ , and the probability that $A$ or $B$ , occurs is $\frac{1}{2}$ , then the probability of both of them occur together is.
a.
$0.02$
b.
$0.20$
c.
$0.01$
d.
$0.10$
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Q74 nat
Let a line $y=mx(m> 0)$ , intersect the parabola, $y^{2} =x$ , at a point $P,$ other than the origin. Let the tangent to it a $P$ , meet the $x$ -axis at the point $Q.$ If area $(\Delta OPQ) = 4$ square unit, then $m$ is equal to
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Q75 nat
The sum, $\sum ^{7}_{n=1} \frac{n(n+1)(2n+1)}{4}$ , is equal to
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