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# JEE Mains 2021 Question Paper with Solutions- 24 Feb P1

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Posted by Mahak Jain, 16/3/2021

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Attempting question papers is best way to practice. In this blog you have JEE Mains 2021 question paper with solutions for 24th February shift 1.

In this blog we provide you JEE Mains 2021 question paper with solutions for free. Here at Kunduz we aim to provide quality solutions from best tutors at Kunduz. These solutions for JEE Mains 2021 question paper are prepared by Kunduz tutors.

## Important Material for JEE Aspirants

Must read JEE Mains chapter wise weightage

NCERT Books – Best Ways to Study

## JEE Mains 2021 Question Paper with Solutions- 24 February Shift 1

### Physics

#### Question 1

Match the following for the value of ‘α’ for following process represented by
PVα = constant?

1. a → q, b → s, c → p, d → r

2. a → p, b → r, c → q, d → s

3. a → s, b → p, c → r, d → q

4. a → p, b → r, c → q, d → s

#### Question 2

In a double star system. Find w.

1. w = √(G(m1+m2)/r3)

2. w = √((Gm1m2)/(m1+m2)*r3)

3. w = √((Gm1)/r3)

4. w = √((Gm2)/r3)

#### Question 3

What is the sign of focal length of convex mirror?

1. +ve
2. -ve
3. Can be +ve or -ve
4. None of these

#### Question 4

Find field at center of cube of side a.

1. (4kQ)/(3a2)
2. (8kQ)/(3a2)
3. (16kQ)/(3a2)
4. None of these

#### Question 5

Two equal capacitors are as shown in the two figure 1 and 2. The ratio of the equivalent capacitance in the two diagrams is:-

1. C1/C2 =1/2

2. C1/C2 =1

3. C1/C2 = 1/4

4. None of these

#### Question 6

Compare the magnitudes of moment of Inertia of (masses & Radius are equal)
(b) Disc About ⊥ axis passing through centre (Ib)
(c) SOLID cylinder about (Axis) (Ic)
(d) SOLID sphere (ID)

1. Ia= Ib = Ic >ID

2. Ia= Ib > Ic >ID

3. Ia< Ib < Ic <ID

4. None of these

#### Question 7

A horizontal spring block system (mass m2 spring constant k) is oscillating on a smooth surface with amplitude A. If at the mean position an identical block is kept on it so that they move together after what is the new amplitude?

1. A
2. A/2
3. A/√2
4. A/(2√2)

#### Question 8

How does the energy of photon change if the corresponding wavelength increases?

1. Increases
2. Decreases
3. May increase or decrease
4. Doesn’t depend on wavelength

#### Question 9

In the shown circuit the following the battery is of EMF 4 and internal resistance 8 Ω. Find the potential difference between points x and y is shown in the circuit.

1. Vx -Vy = 2.4V

2. Vy -Vx = -2V

3. Vx -Vy = 4V

4. Vy -Vx= -4V

#### Question 10

Choose the correct a v/s t graph

1.

2.

3.

4.

#### Question 11

If µr & εr represents relative permeability of Medium & Relative permittivity of medium & speed of light in medium is , c/µ
where μ (refractive Index) will be –

1. µrεr
2. √(µrεr)
3. 1/√(µrεr)
4. None of these

#### Question 12

A body cools from 100oC to 90oC in 20 mins. Find the time to cool from 110oC to 100oC.

1. Equal to 20 mins
2. Less than 20 mins
3. More than 20 mins
4. 30 min

#### Question 13

An object is moving with speed v and collides with an identical mass at rest. After collision, they both move at an angle of 30o with original direction. Find ratio of final speed of mass to the initial speed?

1. 1/2
2. 2
3. √3
4. 1/√3

#### Question 14

In a cyclic process ABCA, the process BC is isothermal. Find the work done by gas in cycle ABCA? (Given: P1 = P)

1. 2ln2 PV
2. (2ln2 – 1) PV
3. PV ln2
4. None of these

#### Question 15

A proton & Li3+ are accelerated through same potential difference. If
mass of Li3+ is 8.3 times the mass of proton, then find the ratio of de-Broglie wavelength λLi3+ / λp

1. 0.1
2. 0.2
3. 0.3
4. 0.4

#### Question 16

For a transistor emitter current is 40 mA and collector current is 35 mA, then the β of the transistor is?

1. 8/7
2. 1/7
3. 7
4. 1/8

#### Question 17

Choose the correct option (s) regarding the Hydrogen spectrum

1. A is the series limit of Lyman
2. B is the third line of Balmer
3. C is the second line of Paschen
4. All of the above are correct

#### Question 18

If W = work done, T = Temperature, Kb = Boltzmann constant, x=Displacement & W=αβ2 e-(x2)/(αTKB) then find dimensions of β?

1. [M1 L2 T-2 ]

2. [M-1 L2 T-2 ]

3. [M1 L1 T-2 ]

4. None of these

#### Question 19

Find the current at time t = 3 seconds, If the charge as a function of time is given as q(t) =3t2 + 2t + 1.

1. 34A
2. 21A
3. 20A
4. 15A

#### Question 20

Two satellites are revolving in the orbit around a planet. The ratio of their time periods is 1 : 8. Find the ratio of their angular velocities.

1. w1 /w2 = 1/2

2. w1 /w2 = 8

3. w1 /w2 = 2

4. w1 /w2 = 2/3

#### Question 21

Find the minimum force Fo that should be applied to the block of mass m = 0.5 kg, so that the block stays in equilibrium with the rough vertical wall having friction coefficient μ = 0.2. (Take g = 10 m/s2 ) (Answer to the nearest integer).

#### Question 22

A vertical cross-section of plane is y= x2 /4 coefficient of friction is 0.5. Find
maximum height at which particle can stay (in cm).

#### Question 23

Two identical particles of same mass are shown just before collision and just after collision than v1 /v2 is :

#### Question 24

i =20t +8t2
Find charge flown during 0≤t≤15

#### Question 25

A Zener diode is connected in the circuit as shown. The current in the 2k Ω
resistance is x ×10-4 A , where x is:

#### Question 26

A 220 volts AC supply is given to the primary circuit of transformer and as output of 12 volts DC is taken out using rectifier. If secondary number of urns was 24, then find the no. of turns in primary coil.

#### Question 27

A 100 kg block can be lift by placing a mass m on a piston (hydraulic lift). If diameter of piston placed at one and is increased by 4 times and that of second piston is decreased by 4 times. Now same mass m is placed at piston than how many kg weight can be lift up for the new set up?

#### Question 28

An electromagnetic wave is propagating in medium, where µrr=2. If speed of light in medium is x×107 m/s. Find out x.

#### Question 29

Vm = 20sin[100πt + π/4]

Vc = 80sin[104πt + π/6]

For amplitude modulation wave find out percentage modulation index.

#### Question 30

In AC series R-L-C resonance circuit Resistance R = 6.28 ohm, frequency 10 MH Z and self inductance L=2×10-4 Henry is given. Find Quality factor of circuit.

## JEE Main Frequently Asked Questions (FAQs)

Question 1: When is JEE mains 2021 exams?

Answer: National Testing Agency has announced dates for all phases of JEE Mains. First phase is in February 2021 (23, 24, 25 and 26). Second phase is in March 2021 (15, 16, 17 & 18) , third in April 2021 (27, 28, 29 & 30) and fourth in May 2021 (24, 25, 26, 27 & 28). To get more details about JEE Mains click here.

Question 2: Can I challenge JEE Mains 2021 answer key? How?

Answer: Yes, candidates who have objection to the answer key given by National Testing Agency can go to jeemain.nta.nic.in , from where they can challenge answer key.

Question 3: Does National Testing Agency refund JEE Mains 2021 answer key fees.

Answer: Yes, National Testing Agency refund fees if objection is found valid with proper supporting documents.

Question 4: Who will conduct JEE Mains 2021 Counseling?

Answer: Joint Seat Allocation Authority (JoSAA) is responsible for counseling of JEE Mains 2021 qualified students.

## Importance of Doubt Clearing with Solving JEE Mains Question Paper

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