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

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

### Physics

#### Question 1

Two electrons are fixed at a separation of 2d from each other. A proton is placed at the midpoint and displaced slightly in a direction perpendicular to line joining the two electrons. Find the frequency of oscillation of proton.

1. f = (1/2π)×√(2ke^{2}/md^{3})

2. f = (1/2π)×√(ke^{2}/md^{3})

3. f = (1/2π)×√(ke^{2}/2md^{3})

4. None of these

Correct answer: 1

#### Question 2

The weight of a person on pole is 48 kg then the weight on equator is?

Given [R = 6400 km]

- 48
- 48.83
- 47.84
- 47

Correct answer: 3

#### Question 3

Two bodies A & B have masses 1 kg & 2 kg respectively have equal momentum. Find the ratio of kinetic energy?

- 1: 1
- 2: 1
- 1: 4
- 1: 2

Correct answer: 2

#### Question 4

Which transition in hydrogen spectrum has the maxima frequency?

- 3 ➝ 2
- 5 ➝ 4
- 9 ➝ 5
- 2 ➝ 1

Correct answer: 4

#### Question 5

A rod of mass M, length L is bent in the form of hexagon. Then MOI about axis passing through geometric centre & perpendicular to plane of body will be ?

- 6ML
^{2} - ML
^{2}/6 - ML
^{2}/2 - 5ML
^{2}/216

Correct answer: 4

#### Question 6

Find the time period of SHM of the block of mass M.

1. T = 2π√(M/2K)

2. T = 2π√(M/K)

3. T = 2π√(2M/2)

4. T = 2π√(M/4K)

Correct answer: 1

#### Question 7

A particle is projected on x axis with velocity v. A force is acting on it in opposite direction , which is proportional to the square of its position. At what distance from origin the particle will stop. [mass is m and constant of proportionality → k]

- ∛(mv
_{o}^{2}/k) - ∛(3mv
_{o}^{2}/k) - ∛(3mv
_{o}^{2}/2k) - ∛(mv
_{o}^{2}/2k)

Correct answer: 3

#### Question 8

Two cars are approaching each other each moving with a speed v. Find the beat frequency as heard by driver of one car both are emitting sound of frequency of.

1. Beat frequency = 2vf_{o}/(C-v)

2. Beat frequency = 2vf_{o}/(C+v)

3. Beat frequency = vf_{o}/(C-v)

4. None of these

Correct answer: 1

#### Question 9

Find the flux of point charge ‘q’ through the square surface ABCD as shown

- q/6∊
_{o} - q/∊
_{o} - q/4∊
_{o} - q/2∊
_{o}

Correct answer: 1

#### Question 10

If a solid cavity whose diameter is removed from a solid sphere of radius R, then the com of remaining part is at?

1. x = -R/3

2. x = -R/7

3. x = -R/6

4. x = -R/14

Correct answer: 3

#### Question 11

In a YDSE experiment, if Red light is replaced by violet light then the fringe width will be

- decrease
- increase
- may increase or decrease
- None of these

Correct answer: 1

#### Question 12

The graph of V versus x in an SHM is (v : velocity, x : displacement)

1.

2.

3.

4.

Correct answer: 4

#### Question 13

If the de Broglie wavelengths of an alpha particle and a proton are the same, then the ratio of their velocities is:

- 1/4
- 4
- 1/2
- 1

Correct answer: 1

#### Question 14

Find the current through the battery just after the key is closed.

- 9/4 A
- 9/2 A
- 9 A
- None of these

Correct answer: 1

## 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 Main 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 Main 2021 qualified students.

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