Practice problems on JEE Mains, JEE Mains 2021 July 27 Shift 2

Question 1

Consider the above reaction, and choose the correct statement:

Accepted Answer

Compound A will be the major product

Answer

Both compounds A and B are formed equally

Answer

Compound B will be the major product

Answer

The Reaction is not possible in acidic medium

Question 2

Which one of the following set of elements can be detected using sodium fusion extract?

Accepted Answer

Sulfur, Nitrogen, Phosphorous, Halogens

Answer

Phosphorous, Oxygen, Nitrogen, Halogen

Answer

Halogens, Nitrogen, Oxygen, Sulfur

Answer

Nitrogen, Phosphorous, Carbon, Sulfur

Question 3

Given below are two statement : one is labelled as Assertion A and the other is labelled as Reason R .Assertion A:SO2​( g) is adsorbed to a larger extent than H2​( g) on activated charcoal.Reason R:SO2​( g) has a higher critical temperature than H2​( g). In the light of the above statements, choose the most appropriate answer from the options given below.

Accepted Answer

Both A and R are correct and R is the correct explanation of A

Answer

A is not correct but R is correct.

Answer

Both A and R are correct but R is not the correct explanation of A

Answer

A is correct but R is not correct

Question 4

The value of limx→∞​(31−sinx​−31+sinx​x​) is equal to :

Accepted Answer

-4

Answer

-1

Answer

4

Answer

0

Question 5

The number of neutrons and electrons, respectively, present in the radioactive isotope of hydrogen is:

Accepted Answer

2 and 1

Answer

1 and 1

Answer

2 and 2

Answer

3 and 1

Question 6

Match List-I with List-II :

Accepted Answer

(a)−(iii),(b)−(iv),(c)−(i),(d)−(ii)

Answer

(a)−(i),(b)−(ii),(c)−(iii),(d)−(iv)

Answer

(a)−(iii),(b)−(iv),(c)−(ii),(d)−(i)

Answer

(a)−(iv),(b)−(i),(c)−(iii),(d)−(ii)

Question 7

Let the mean and variance of the frequency distribution  x:f:​x1​=24​x2​=64​x3​=8α​x4​=9β​ be 6 and 6.8 respectively. If x3​ is changed from 8 to 7 , then the mean for the new data will be :

Accepted Answer

317​

Answer

5

Answer

4

Answer

316​

Question 8

For real numbers α and β=0 if the point of intersection of the straight lines 1x−α​=2y−1​=3z−1​ and βx−4​=3y−6​=3z−7​ lies on the plane x+2y−z=8 , then α−β is equal to:

Accepted Answer

7

Answer

5

Answer

3

Answer

9

Question 9

Compound A gives D-Galactose and D-Glucose on hydrolysis. The compound A is :

Accepted Answer

Lactose

Answer

Sucrose

Answer

Amylose

Answer

Maltose

Question 10

An electron and proton are separated by a large distance. The electron start approaching the proton with energy 3eV . The proton captures the electron and form a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4000A˚ . What is the maximum kinetic energy of the emitted photoelectron ?

Accepted Answer

1.41eV

Answer

No photoelectron would be emitted

Answer

7.61eV

Answer

3.3eV

Question 11

A student appeared in an examination consisting of 8 true-false type question. The student guesses the answer with equal probability. The smallest value of n, so that the probability of guessing at least ' n ' correct answers is less than 21​ , is :

Accepted Answer

5

Answer

6

Answer

3

Answer

4

Question 12

Statement-I : Hyperconjugation is a permanent effect.Statement-II : Hyperconjugation in ethyl cation (CH3​−CH2+​) involves the overlapping of Csp2​−H1 s​ bond with empty 2p-orbital of other carbon.Choose the correct option:

Accepted Answer

Statement I is correct but statement II is false

Answer

Both statement I and statement II are true

Answer

Statement I is incorrect but statement II is true

Answer

Both statement I and statement II are false

Question 13

To an aqueous solution containing ions such as Al3+,Zn2+,Ca2+,Fe3+,Ni2+,Ba2+ and Cu2+ was added conc. HCl , followed by H2​ S .The total number of cations precipitated during this reaction is/are:

Accepted Answer

1

Answer

2

Answer

3

Answer

4

Question 14

An automobile of mass 'm' accelerates starting from origin and initially at rest, while the engine supplies constant power P . The position is given as a function of time by :

Accepted Answer

(9m8P​)1/2t3/2

Answer

(8 m9P​)1/2t3/2

Answer

(8P9m​)1/2t3/2

Answer

(9m8P​)1/2t2/3

Question 15

The CORRECT order of first ionisation enthalpy is :

Accepted Answer

Al<Mg<S<P

Answer

Mg<Al<P<S

Answer

Mg<S<Al<P

Answer

Mg<Al<S<P

Question 16

A simple pendulum of mass ' m ', length ' ℓ ' and charge +q ' suspended in the electric field produced by two conducting parallel plates as shown. The value of deflection of pendulum in equilibrium position will be :

Accepted Answer

tan−1[mgq​×(C1​+C2​)(d−t)C2​( V1​+V2​)​]

Answer

tan−1[mgq​×(C1​+C2​)(d−t)C1​( V2​−V1​)​]

Answer

tan−1[mgq​×(C1​+C2​)(d−t)C1​( V2​+V2​)​]

Answer

tan−1[mgq​×(C1​+C2​)(d−t)C2​( V2​−V1​)​]