JEE Main 2021 Answer Key and Solutions- 25 Feb C1

JEE Main 2021 Answer Key (Official) for February session has been released. It is released separately for four session in February, March, April and May sessions. JEE Main is conducted for providing admission into UG engineering (B.Tech) / architecture courses (B.Arch). These courses are offered by various IITs, NITs and IIITs and other government and non-government engineering institutions. JEE Mains answer key is released by the National Testing Agency (NTA). Through this blog, candidates can get the JEE Mains Answer Keys 2021 and also previous year answer key and question papers with solutions.

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JEE Mains 2021 Answer Key with Solutions- 25 February Shift 1

Chemistry Answer Key JEE Mains 2021 25 Feb Shift 1

Question 1

Which one of the following reactions will not form acetaldehyde?

Correct answer: 1

Question 2

Given below are two statements:

Statement-I: CeO₂ can be used for oxidation of aldehyde and ketones.

Statement-II: Aqueous solution of EuSO₄ is a strong reducing agent.

In the light of the above statements, choose the correct answer from the options given below:

1. Both Statement I and Statement II are false
2. Both Statement I and Statement II are true
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

Correct answer: 2

Question 3

Given below are two statements:

Statement-I : An allotrope of oxygen is an important intermediate in the formation of reducing smog.

Statement-II: Gases such as oxides of nitrogen and sulphur present in troposphere contribute to the fomation of photochemical smog.

In the light of the above statements, choose the correct answer from the options given below:

1. Statement I is true but Statement II is false
2. Both Statement I and Statement II are false
3. Statement I is false but Statement II is true
4. Both Statement I and Statement II are true

Correct answer: 2

Question 4

Which of the glycosidic linkage between galactose and glucose is present in lactose?

1. C-1 of galactose and C-4 of glucose

2. C-1 of glucose and C-6 of galactose

3. C-1 of galactose and C-6 of glucose

4. C-1 of glucose and C-4 of galactose

Correct answer: 1

Question 5

In which of the following pairs, the outer most electronic configuration will be the same?

1. Ni²⁺ and Cu⁺
2. Fe²⁺ and Co⁺
3. Cr⁺ and Mn²⁺
4. V²⁺ and Cr⁺

Correct answer: 3

Question 6

The major product of the following chemical reaction is:

1. CH₃CH₂CH₃

2. CH₃CH₂CH₂OH

3. CH₃CH₂CHO

4. (CH₃CH₂CO)₂O

Correct answer: 3

Question 7

Identify A and B in the chemical reaction.

1.

2.

3.

4.

Correct answer: 1

Question 8

Ellingham diagram is a graphical representation of :

1. △H vs T

2. △G vs P

3. △G vs T

4. (△G – T△S) vs T

Correct answer: 3

Question 9

Compound(s) which will liberate carbon dioxide with sodium bicarbonate solution is/ are :

1. B only
2. C only
3. A and B only
4. B and C only

Correct answer: 4

Question 10

In Freundlich adsorption isotherm at moderate pressure, the extent of adsorption x/m is directly proportional to P^x. The value of x is:

1. Zero
2. 1
3. ∞
4. 1/n

Correct answer: 4

Question 11

Identify A in the given chemical reaction.

1.

2.

3.

4.

Correct answer: 2

Question 12

According to molecular orbital theory, the species among the following that does not exist is

1. He₂^–
2. Be₂
3. He₂⁺
4. O₂^2-

Correct answer: 2

Question 13

The plots of radial distribution functions for various orbitals of hydrogen atom against ‘r’ are given below

The correct plot for 3s orbital is

1. C
2. D
3. B
4. A

Correct answer: 2

Question 14

The solubility of AgCN in a buffer solution of pH = 3 is x. The value of x is :

[Assume : No cyno complex is formed; K_sp(AgCN) = 2.2 × 10^-16 and K_a(HCN) = 6.2 × 10^-10]

1. 1.9 × 10^–5
2. 1.6 × 10^–6
3. 2.2 × 10^–16
4. 0.625 × 10^–6

Correct answer: 1

Question 15

The hybridization and magnetic nature of [Mn(CN)₆]^4– and [Fe(CN)₆]^3–, respectively are

1. d²sp³ and paramagnetic
2. d²sp³ and diamagnetic
3. sp³d² and paramagnetic
4. sp³d² and diamagnetic

Correct answer: 1

Question 16

Complete combustion of 1.80 g of an oxygen containing compound (C_xH_yO_z) gave 2.64 g of CO₂ and 1.08 g of H₂O. The percentage of oxygen in the organic compound is :

1. 50.33
2. 53.33
3. 51.63
4. 63.53

Correct answer: 2

Question 17

Which of the following equation depicts the oxidizing nature of H₂O₂?

1. 2I^– + H₂O₂ + 2H⁺ → I₂ + 2H₂O
2. KIO₄ + H₂O₂ → KIO₃ + H₂O + O₂
3. Cl₂ + H₂O₂ → 2HCI + O₂
4. I₂ + H₂O₂ + 2OH^– → 2I^– + 2H₂O + O₂

Correct answer: 1

Question 18

Which statement is correct?

1. Buna-S is a synthetic and linear thermosetting polymer.
2. Buna-N is a natural polymer.
3. Synthesis of Buna-S needs nascent oxygen.
4. Neoprene is an addition copolymer used in plastic bucket manufacturing.

Correct answer: 3

Question 19

Which of the following reaction/s will not give p-aminoazobenzene?

1. C only
2. B only
3. A only
4. A and B

Correct answer: 2

Question 20

The correct statement about B₂H₆ is :

1. Terminal B – H bonds have less p-character when compared to bridging bonds.
2. All B – H – B angles are of 120°.
3. The two B – H – B bonds are not of same length.
4. Its fragment, BH3, behaves as a Lewis base.

Correct answer: 1

Question 21

For the reaction, aA + bB → cC +dD, the plot of log k vs 1/T is given below:

The temperature at which the rate constant of the reaction is 10^–4s^–1 is __ K. (Rounded-off to the nearest integer)

[Given : The rate constant of the reaction is 10^–5s^–1 at 500 K.]

Correct answer: 526

Question 22

0.4 g mixture of NaOH, Na₂CO₃ and some inert impurities was first titrated with N/10 HCl using phenolphthalein as an indicator, 17.5 mL of HCl was required at the end point. After this methyl orange was added and titrated. 1.5 mL of same HCl was required for the next end point. The weight percentage of Na₂CO₃ in the mixture is __. (Rounded-off to the nearest integer)

Correct answer: 4

Question 23

The reaction of cyanamide, NH₂CN(s) with oxygen was run in a bomb calorimeter and △U was found to be –742.24 kJ mol^–1. The magnitude of △H₂₉₈ for the reaction NH₂CN(s) + 1.5 O₂(g) → N₂(g) + CO₂(g) + H₂O(l) is __ kJ. (Rounded off to the nearest integer) [Assume ideal gases and R=8.314 J mol–1 K–1]

Correct answer: 741

Question 24

Consider the following chemical reaction.

The number of sp2 hybridized carbon atom(s) present in the product is __.

Correct answer: 7

Question 25

In basic medium CrO₄^2- oxidises S₂O₃^2- to form SO₄^2- and itself changes into Cr(OH)₄^–. The volume of 0.154 M CrO₄^2- required to react with 40 mL of 0.25 M S₂O₃^2- is __ mL. (Rounded-off to the nearest integer)

Correct answer: 173

Question 26

Among the following, the number of halide(s) which is/are inert to hydrolysis is __.

1. BF₃
2. SiCl₄
3. PCl₅
4. SF₆

Correct answer: 1

Question 27

A car tyre is filled with nitrogen gas at 35 psi at 27°C. It will burst if pressure exceeds 40 psi. The temperature in °C at which the car tyre will burst is __. (Rounded-off to the nearest integer)

Correct answer: 70

Question 28

The ionization enthalpy of Na⁺ formation from Na(g) is 495.8 kJ mol^–1, while the electron gain enthalpy of Br is –325.0 kJ mol^–1. Given the lattice enthalpy of NaBr is –728.4 kJ mol–1. The energy for the formation of NaBr ionic solid is (–) _ × 10^–1 kJ mol^–1.

Correct answer: 5576

Question 29

Using the provided information in the following paper chromatogram :

Fig : Paper chromatography for compounds A and B.

The calculated R_f value of A __ × 10^–1.

Correct answer: 4

Question 30

1 molal aqueous solution of an electrolyte A₂B₃ is 60% ionised. The boiling point of the solution at 1 atm is __ K. (Rounded-off to the nearest integer)

[Given K_b for (H₂O) = 0.52 K kg mol^–1]

Correct answer: 375

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