JEE Main 2020 Mock Test - 1


75 Questions MCQ Test JEE Main Mock Test Series 2020 & Previous Year Papers | JEE Main 2020 Mock Test - 1


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This mock test of JEE Main 2020 Mock Test - 1 for JEE helps you for every JEE entrance exam. This contains 75 Multiple Choice Questions for JEE JEE Main 2020 Mock Test - 1 (mcq) to study with solutions a complete question bank. The solved questions answers in this JEE Main 2020 Mock Test - 1 quiz give you a good mix of easy questions and tough questions. JEE students definitely take this JEE Main 2020 Mock Test - 1 exercise for a better result in the exam. You can find other JEE Main 2020 Mock Test - 1 extra questions, long questions & short questions for JEE on EduRev as well by searching above.
QUESTION: 1

The volumes of containers A and B, connected by a tube and a closed valve are V and 4 V, respectively. Both the containers A and B have the same ideal gas at pressures (temperatures) 5.0 ×105 Pa(300 K) and 1.0 ×105Pa (400 K), respectively. The valve is opened to allow the pressure to equalise, but the temperature of each container is kept constant at its initial value. Find the common pressure in the containers.

Solution:

∴ p1 > p2 so, the equalise pressure of the p is reduced from p1

Given, T1 = 300

T2 = 400

V2 = 4V

p1 = 5 x 105

QUESTION: 2

A block of mass 10 kg is suspended through two light spring balances as  shown in figure

Solution:

The FED of the spring balances and the block are as shown in figure.

T1=10g T1=T2 ⇒ T2=10g where, T1 and Tare readings of spring balances as shown in figure.

QUESTION: 3

If E = 100 sin (100t) volt and are the instantaneous values of voltage and current, then the R.M.S values of voltage and current are respectively.

Solution:

The instantanous valur of voltae is 

E= 100sin (100 t) V ...(1)

 (compare it with

E = Esin (ωt) V

we get,

E= 100 V, ω = 100 rads-1

the r.m.s value of voltage is 

The instantaneous value of current is 

compare it with, I=I0sin(ω t + Φ)

we get

I0 = 100 mA, ω = 100 rads-1

The r.m.s value of current is

QUESTION: 4

Two spherical bodies of mass M and 5 M and radii R and 2 R, respectively are released in free space with initial separation between their centres equal to 12 R. If they attract each other due to gravitational force only, then the distance covered by the smaller body just before collision is

Solution:

Initial separation between both centers = 12R
Final separation (when collision occurs) = 3R
Thus both the centers need to travel 9R combinely in such a way that their COM does not move as no external force is acting over the 2 mass system.
Thus let say if smaller mass travel x distance, bigger would eventually travel rest 9R - x
Thus we we write the equation of displacement of the COM, and taking direction of displacement of bigger mass as positive, we get
M (-x) + 5M (9R - x) / (M + 5M) = 0
Thus we get, -Mx + 45MR - 5Mx = 0
We get 6x = 45R
Thus x = 7.5R

QUESTION: 5

Mark the correct option.

Solution:

A charge moving along a circle is equivalent to a current carrying coil, but with respect to magnetic field on the axis of circle. It is equivalent only for the average value of the magnetic field and not for instantaneous values. While if two charge particles are moving symmetrically along a circle at diametrically opposite points then the average as well as instantaneous magnetic field on its axis is same as due to a current carrying coil.

QUESTION: 6

The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be

Solution:

Initial volume = final volume

QUESTION: 7

Students I, II and III perform an experiment for measuring the acceleration due to gravity (g) using a simple pendulum. They use different lengths of the pendulum and /or record time for different number of oscillations. The observations are shown in the table.

Least count for length = 0.1 cm

Least count for time = 0.1 s

If EI, EII and EIII are the percentage errors in g, i.e.,

for students I, II and III, respectively, then

Solution:

The period of oscillation (T) of a simple pendulum of length ℓ is given by

T = 2π√(ℓ/g)

Therefore, g = 4π2 ℓ/T2 so that the fractional error in g is given by

∆g/g = (∆ℓ/ℓ) + 2(∆T/T)

[The above expression is obtained by taking logarithm of both sides and then differentiating. Note that the sign of the second term on the RHS is changed from negative to positive since we have to consider the maximum possible error].

Here ∆ℓ = 0.1 cm and ∆T = 0.1 s

The percentage error is 100 times the fractional error so that

EI = ∆g/g = [(0.1/64) + 2(0.1/128)]×100 = 5/16 %,

EII = ∆g/g = [(0.1/64) + 2(0.1/64)]×100 = 15/32 % and

EIII = ∆g/g = [(0.1/20) + 2(0.1/36)]×100 = 19/18 %

Thus EI is minimum. 

QUESTION: 8

Write down the expression for capacitance of a spherical capacitor whose conductors radii are Rand R2(R2>R1),when inner sphere is grounded.

Solution:

QUESTION: 9

A mass of M kg is suspended by a weightless string. The horizontal force that is required to displace it until the string makes an angle of 45° with the initial vertical direction is

Solution:

Here, position 1 and position 2 can be calculated by using 

work- energy Theorem


QUESTION: 10

Acceleration of each block is given as g/5√2. Find the magnitude and direction of force exerted by string on pulley. (μ = 0.4)

Solution:

Let coefficient of friction be u. and and 3m block is moving down the incline, then Acceleration  

 

Force exerted by string/on pulley is √2T as shown in figure

∴ F = 6mg/5

QUESTION: 11

A pipe of length 85 cm is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below 1250 Hz. The velocity of sound in air is 340 m/s.

Solution:

for closed pipes,

so in this case 6 possibilities

QUESTION: 12

Three identical spheres, each of mass 1 kg are kept as shown in the figure below, touching each other, with their centres on a straight line. If their centres are marked P, Q, R respectively, the distance of centre of mass of the system from P is

Solution:

Radius

r1= 0

r2 = PQ

r3 = PR

the distance of centre of mass of the system from 'P' is given by

QUESTION: 13

A resistor R and 2μF capacitor in series is connected through a switch to 200 V direct supply. Across the capacitor is a neon bulb that lights up at 120 V. Calculate the value of R to make the bulb light up 5 s after the switch has been closed (log10 2.5 = 0.4)

Solution:

Wen Neon bulb is fulled with gas.

No, current frows through it because the resistance is infine.

QUESTION: 14

A α−particle passes through a potential difference of 2×106V and then it becomes incident on a silver foil. The charge number of silver is 47. The energy of incident particles will be: (in joule)

Solution:

Energy of incident particles ie, alpha particles will be 

QUESTION: 15

Direction: Question is based on the following paragraph.

A wire of length L, mass m and carrying a current is suspended from point O as shown. An infinitely long wire carrying the same current I is at a distance L below the lower end of the wire. Given, I = 2A, L= 1m and m = 0.1 kg (ln 2 = 0.693)

Q. What is angular acceleration of the wire just after it is released from the position shown?

Solution:

 

QUESTION: 16

The figure shows three circuits with identical batteries, inductors and resistances. Rank the circuits according to the currents through the battery just after the switch is closed, greatest first

Solution:

Just before closing the switch.


so
i2 > i3 >i1 (i1 = 0) After a long time closing the switch 

Hence  i2>i3>i1

QUESTION: 17

A bullet when fired into a fixed target loses half of its velocity after penetrating 20 cm.How much further it will penetrate before coming to rest?

Solution:

 

QUESTION: 18

Directions: Question are Assertion - Reaction type each of these contains two statements: Statement I (Assertion), Statement II (Reason) Each of these questions also has four alternative choices, only one of which is correct. You have to select the correct choices from the codes a, b, c and d given below:

Statement I : The isothermal curves intersect each other at a certain point

Statement II: The isothermal changes takes place slowly, so the isothermal curves have very little slope.

Solution:

To carry out isothermal process, a perfect gas is compressed or allowed to expand very slowly. Isothermal curves never intersect each other as they have very little slope.

QUESTION: 19

A parallel plate air capacitor has a capacitance C. When it is half filled with a dielectric of dielectric constant 5, the percentage increase in the capacitance will be

Solution:

∴ increase in capiacitance

QUESTION: 20

A ball is dropped from a bridge at a height of 176.4 m over a river. After 2s, a second ball is thrown straight downwards. What should be the initial velocity of the second ball so that both hit the water simultaneously?  (Take g=10m/s2)

Solution:

for second ball

*Answer can only contain numeric values
QUESTION: 21

Directions: The answer to this question is a single-digit integer, ranging from 0 to 9. Enter the correct digit in the box given below. 

Q. A 40 cm diameter pipe branches into two pipes of diameters 10 cm and 20 cm each. If the average velocities of water that flows through 10 cm and 20 cm pipes are 6 m/s and 2 m/s, respectively, then the speed of the water that flows through the 40 cm pipe (in m/s) is 

(Answer up to nearest integer)


Solution:

Let x be the velocity of water flowing through 40 cm diameter branch
V(40): Volume of water flowing through 40cm diameter
V(20): Volume of water flowing through 20cm diameter
V(10): Volume of water flowing through 10cm diameter
V(40) = V(20) + V(10) - - - (1)
Volume of water flowing = (Cross-sectional area) * (Velocity of water)
(1) → x*π (0.20)2 = 2*π (0.10)2 + 6*π (0.05)2
x*(0.04) = 2*(0.01) + 6*(0.0025)
x = (0.035) / (0.04) = 35/40 = 0.875
Nearest integral value is 1

*Answer can only contain numeric values
QUESTION: 22

Directions: The answer to this question is a single-digit integer, ranging from 0 to 9. Enter the correct digit in the box given below. 

Q. Two point objects A and B are 40 cm apart. A convex lens L of focal length 15 cm should be placed in between them such that the images due to the two point objects coincide. If the least distance between L and A is x, then the value of x – 1 is


Solution:

Let VA be the image distance due to the object A. X is the distance between the object A and the lens.

image due to the second object:

As one of the images should be virtual in order to satisfy the given condition.


the lesser value is 10. Hence, the value of x-1 = 9

*Answer can only contain numeric values
QUESTION: 23

Directions: The answer to this question is a single-digit integer, ranging from 0 to 9. Enter the correct digit in the box given below. 

Q. An air-filled parallel plate capacitor having circular plates has a capacitance of 10 pF. When the radii of the plates are increased two times, the distance between them is halved and if a medium of dielectric constant k is introduced, the capacitance increases 16 times. The value of k is


Solution:

*Answer can only contain numeric values
QUESTION: 24

Directions: The answer to this question is a single-digit integer, ranging from 0 to 9. Enter the correct digit in the box given below. 

Q. Two parallel identical plates carry equal and opposite charges having a uniform charge of 88.9 C. Positive plate is fixed on the ceiling of a box and the negative plate has to be suspended. If the area of the plates is 6.35 sq. m and 'm' is the mass of the negative plate, then the value of [m] in kg, where [ ] stands for maximum integer value, is


Solution:

force of attraction between the plates = weight of the negative plate for it to be suspended

*Answer can only contain numeric values
QUESTION: 25

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

A radioactive sample S1 having an activity of 5 μ Ci and half life of 20 years has twice the number of nuclei as another sample S2, which has an activity of 10 μCi. The half lives (in years) of S2 is


Solution:

QUESTION: 26

Directions: Questions are based on the following paragraph.

When ammonium vanadate is heated with oxalic add solution, a compound Z is formed. A sample of Z was titrated with KMnO4 solution in hot acidic solution. The resulting liquid was reduced with SO2, the excess SOboiled off, and the liquid again titrated with KMnO4. The ratio of the volumes of KMnO4 used in the two titrations was 5 : 1. KMnO4 oxidises all oxidation state of vanadium to Vanadium (+V) and SO2 reduces vanadium (+V) to vanadium (+IV). Read the above experiment and answer the following questions. If vanadium exists as , reduced species by SO2 would be

Solution:

 is reduced to +4 oxidation state which is 

QUESTION: 27

In a cubic dosed packed structure of mixed oxides, the lattice is made up of oxide ions, one eighth of tetrahedral/voids are occupied by divalent ions (A2+), while one half of the octahedral voids are occupied by trivalent ions(B3+)What is the formula of the oxide ?

Solution:

Let number of oxides = x

Number of octahedral void = x

Number of tetrahedral void = 2x

Number of 

 

 Hence, formula of oxide is AB2O4.

QUESTION: 28

Which of the following sequence of reaction is the best means to furnish the conversion RCH2OH→RCH2NH2

Solution:

QUESTION: 29

The standard heat of combustion of carbon(s), sulphur (s) and carbon disulphide (l) are -393.3, -293.72 and - 1108.76 kJ/mol respectively. The standard heat of formation of carbon disulphide(l) is

Solution:

on putting various enthalpy of formation in equation III 

(reactants) - 1108.76 = [-393.3 + 2(-293.72)] - 

=-1108.76 = -393.3 -2 x 293.72 - 

QUESTION: 30

The volume of 0.1 M oxalic acid that can be completely oxidised by 20 mL of 0.025 M KMnO4 solution is

Solution:

QUESTION: 31

α-D(+)-glucose and β-D-(+)-glucose are

Solution:

Anomers are diastereo isomers of cyclic forms of sugars or similar molecules differing in the configuration at the anomeric carbon (C-1 atom of aldose or the  C-2 atom of a 2-ketose).The cyclic forms of carbohydrates can exist in two forms , α – and β- based on the position of the substituent at the anomeric centre.

QUESTION: 32

Match List I with List II and select the correct answer using the codes given below the lists:

Solution:

Cyanide process is used for the extraction of Au, floatation process uses pine oil as a foaming agent, electrolytic reduction is used in the extraction of Al and zone refining process produces ultra pure Ge.

QUESTION: 33

Which one of the following is the structure of polyacrylonitrile?

Solution:

Polyacrylonitrile has molecular formula (C3H3N)n.

Hence its structure is

QUESTION: 34

In the hydrocarbon 

The state of hybrization of carbons 1,3 and 5 are in the following sequence :

Solution:

Among the four (I) and (II) have chirality . so, here, optical isomers are obtained.

QUESTION: 35

If for  then the value of keq for the reaction  will be

Solution:

for reaction

QUESTION: 36

For the elementary reaction M → N, the rate of disappearance of M increases by factor of 8 upon doubling the concentration of M. The order of the reaction with respect to M is

Solution:

On doubling cone of [M], Rate becomes 8 times

QUESTION: 37

Calgon used as a water softener is

Solution:

Clark’s process involves the addition of a controlled quantity of slaked line (calicium hydroxide)

Slaked line is itself a source of calcium ions (and hence hardness), So care must be taken to avoid adding an excess

QUESTION: 38

In which of the following case, increase in concentration of ion cause increase in Ecell?

Solution:

QUESTION: 39

Directions: Questions  are based on the following paragraph.

When ammonium vanadate is heated with oxalic add solution, a compound Z is formed. A sample of Z was titrated with KMnO4 solution in hot acidic solution. The resulting liquid was reduced with SO2, the excess SOboiled off, and the liquid again titrated with KMnO4. The ratio of the volumes of KMnOused in the two titrations was 5 : 1. KMnO4 oxidises all oxidation state of vanadium to Vanadium (+V) and SO2 reduces vanadium (+V) to vanadium (+IV). Read the above experiment and answer the following questions.

Q. What is the oxidation state of vanadium in the compound Z?

Solution:

vanadate ion   is reduce to Vx (species Z) by  

ion in acidic medium. Vis oxidised by 

∴  to which in turn isoxidised to 

volumes of   used in Eqs (1) , (2) are in ratio , of 

  ∴ 

QUESTION: 40

Direction: Question is assertion reason type. These question contains two statements Statement I (Assertion), Statement II (Reason). These question also has four alternative choices, only one of which is correct. You have to select the correct choices from the codes (a), (b), (c) and (d) given below:

Statement I : Detection of chlorine in 2, 4, 6 -trinitrochlorobenzene can be done directly by addition of aq. AgNO3 solution.

Statement II: C-Cl bond is weakened by electron withdrawing - NO2 group

Solution:

2,4, 6 - trinitrocholorobenzene.The presence of electron withdrawing group (like -NO2) makes the nucleophilic aromatic substitution easier, as it decreases the strength of C-Cl bond. Thus,gives ppt. of AgCl with aq. AgNo3

QUESTION: 41

Silver (atomic weight = 108 g mol-1 ) has a density of 10.5 g cm-3. The number of silver atoms on a surface of area 10-12 mcan be expressed in scientific notation as y * 10x . The value of x is

Solution:

since the number of atom of silver 

QUESTION: 42

Names of some compounds are given. Which one is not correct in IUPAC system?

Solution:

Correct IUPAC name is 4-ethyl-3-methyl heptane.

QUESTION: 43

The structure of isobutyl group in an organic compound is :

Solution:

Structure of 1 butene-3yne we know that double bond contains one sigma and one pi-bond while a triple bond contains one sigma and two pi-bonds. So, total number of sigma and pi-bonds.

= (5+1+1) σ + (0+1+2) π i.e 7σ, 3π

1-butene-3yne contains 7 sigma and 3 Pi-bonds

QUESTION: 44

consider the follwing reaction,

the value of x, y and z in the reaction respectively are

Solution:

Given

after balancing the equation, we get

∴ The value of x, y and z in the given equation are 2,5 and 16 respectively

QUESTION: 45

The correct statement about the following disaccharide is

Solution:

In the given structures A and B ring A is 6 membered ring containg one oxygen with α – glycosidic linkage, hence it is pyranose where as ring B is 5- membered ring containing one oxygen is furanos with β – glycosidic linkage.

*Answer can only contain numeric values
QUESTION: 46

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. X x 10-2 moles of NaCl need to be added to precipitate out PbCl2 from 1 L solution of Pb(NO3)2 having concentration 0.01M. If Ksp of PbCl2 at 298K is 1.6 x 10-5, then the value of X will be


Solution:

Hence [NaCl] required 4 x 10-2

Nimber of moles of NaCl to be added = 4 x 10-2

*Answer can only contain numeric values
QUESTION: 47

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. For a diatomic molecule having bond distance , the dipole moment is 1.2 D. What is the integral value obtained as a product of the fraction of charge separated and 16?


Solution:

fraction of electric charge  on ach atom 

*Answer can only contain numeric values
QUESTION: 48

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. On complete combustion of a 9 L mixture of ethane and propane, 21 L of CO2 at STP is produced. The molar ratio of ethane and propane in the mixture is


Solution:

*Answer can only contain numeric values
QUESTION: 49

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. How many open chain structures are possible for N-Methyl butanamine (including it) that are referred to as metamers.


Solution:

Molecular formula of N-methyl butanamine is C5H13N. Primary, secondary and tertiary amines are different functional groups and metamerism cannot coexist with functional isomerism. Hence, we shall consider only those isomers of N-methyl butanamine which are secondary (2o) amines.

Every molecule of group A is a meramer of every molecule in group B

 

*Answer can only contain numeric values
QUESTION: 50

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. 100gm of  is reduced to 3.125 g in 25 days. Half life of bismuth -210 (in days) is


Solution:

QUESTION: 51

A bag contains a white and b black balls. Two players A and B alternately draw a ball from the bag replacing the ball each time after the draw till one of them draws a white ball and wins the game. A begins the game. If the probability of A winning the game is three times that of B, then the ratio a : b is

Solution:

w → drawing white ball at any draw and B that  for a black ball

then

Also P(B wins the game)

QUESTION: 52

If Z is the set of integers. Then, the relation R= {(a, b) :1+ ab > 0} on Z is

Solution:

so it is reflexive

so, it is symmetric 

So, it is not transitive. 

QUESTION: 53

Direction: Question  is Assertion-Reason type question. These question contains two statements: Statement I (Assertion) and Statement II (Reason). These question also has four alternative choices, only one of which is the correct answer. You have to select the correct choice in the cedes (a), (b), (c) and (d) in the given below: 

Statement I: 

Staement II: |x| is non- differential at x = 0

Solution:

Given

 found, since condition on x is not given

 also |x| is nondifferential at x = 0

QUESTION: 54

For any two real numbers θ and ϕ, we define θRϕ , if and only if sec2 θ - tan2ϕ =1. The relation R is

Solution:

QUESTION: 55

Direction: Question is Assertion-Reason type question. These question contains two statements: Statement I (Assertion) and Statement II (Reason). These question also has four alternative choices, only one of which is the correct answer. You have to select the correct choice in the cedes (a), (b), (c) and (d) in the given below: 

Solution:

 

Now statement II is valid only where  

∴ Statement I is true and statement II is false

QUESTION: 56

The value of  

Solution:

QUESTION: 57

the value of 

Solution:

QUESTION: 58

if n≥ 2 is an integer  and I is the identity matrix of order 3. then

 

Solution:

Given

similarly

 

QUESTION: 59

 ax is equal to 

Solution:

Put

put

QUESTION: 60

The number of real solutions of the equation  2x/2+(√2+1)x=(5+2√2)x/2 is

Solution:

Thus no. of real solution is 1.

QUESTION: 61

The function 

Solution:

Using Leibnitz's rule

on differentiating w.r.t θ we get

 

QUESTION: 62

If m1, m2, m3 and m4 are, respectively the magnitudes of the vectors

then the corect order of m1, m2, m3 and m4 is 

Solution:

QUESTION: 63

 is equal to 

Solution:

QUESTION: 64

The area bounded by y = x|sin x| and X - axis between x = 0, x = 2π is

Solution:

QUESTION: 65

the eccenricity of the hyperbola  is

Solution:

QUESTION: 66

If θ is the angle between the tangents from (-1, 0) to the circle x2 + y2 - 5x + 4y - 2 = 0, then θ is equal to

Solution:

we have, angle between the two tangents from (x1,y1)

QUESTION: 67

Let Sk be the sum of an infinite GP series whose first term k is k and common ratio is k/(k + 1) (k> 0). Then, the value of  is equal to

Solution:

QUESTION: 68

Let z1 ≠ z2 and |z1| = |z2|. If z1 has positive real part and z2 has negative imaginary part. Then, 

Solution:

Now,


= a purely imaginary or 0 if (x1/x2 )= (y1/y2)

if (x1/x2 )= (y1/y2) then 

x1 + iy1 = k(x2+iy2)

 is purely imaginary.

QUESTION: 69

, Where [] denotes the greater function is equal to

Solution:

QUESTION: 70

Three vectors   forms

Solution:

*Answer can only contain numeric values
QUESTION: 71

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. if , then the number of solutions of 


Solution:

*Answer can only contain numeric values
QUESTION: 72

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Q. The points (1, 3) and (5, 1) are two opposites vertices of a rectangle and the other two vertices lie on the line y – 2x + C = 0. Then the value of C is


Solution:

Since the diagonals of a rectangle bisect each other, so the point

lies on y = 2x - C, which gives C = 4

*Answer can only contain numeric values
QUESTION: 73

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

Given that α and γ are the roots of the equation Ax2 – 4x + 1 = 0, and β and δ are the roots of the equation Bx2 – 6x + 1 = 0. Find the value of B - A, such that α, β, γ, δ are in H.P.


Solution:

As per the given condition

Let d be the common difference

Adding both of the equations, we get

*Answer can only contain numeric values
QUESTION: 74

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

if  the greatest value of  is


Solution:

*Answer can only contain numeric values
QUESTION: 75

Directions: The answer to the following question is a single digit integer ranging from 0 to 9. Enter the correct digit in the box given below.

if range of the function f(x) = sin–1 x + 2 tan–1 x + x2 + 4x + 1 is [a, b], then the value of a + b is


Solution:

therefore, f(x) is an increasing function. Hence, a is minimum value of f(x). therefore

And, b is maximum value of  f(x) . Therefore 

Therefore, the range of f(x) is . Therefore

Hence, it is required solution.

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