Practice problems on JEE Mains, JEE Mains 2021 Mar 17 Shift 1

Question 1

Team 'A' consists of 7 boys and n girls Team 'B' has 4 boys and 6 girls. If a total of 52 single matches can be arranged between these two teams when a boys plays against a boy and a girl plays against a girl, then n is equal to :

Accepted Answer

4

Answer

6

Answer

5

Answer

2

Question 2

The above reaction requires which of the following reaction conditions ?

Accepted Answer

623 K, 300 atm

Answer

573 K, 300 atm

Answer

573 K, Cu, 300 atm

Answer

623 K, Cu, 300 atm

Question 3

The correct order of conductivity of ions in water is :

Accepted Answer

Cs+>Rb+>K+>Na+

Answer

K∗>Na+>Cs∗>Rb+

Answer

Rb+>Na+>K+>Li+

Answer

Na+>K+>Rb+>Cs+

Question 4

Which of the following reaction is an example of ammonolysis ?

Accepted Answer

C6​H5​CH2​Cl+NH3​⟶C6​H5​CH2​NH2​

Answer

C6​H5​CH2​CN⟶[H]​C6​H5​CH2​NH2​

Answer

C6​H5​COCl+C6​H5​NH2​⟶C6​H5​CONHC6​H5​

Answer

C6​H5​NH2​⟶HCl​C6​H5​ N+H3​Cl−

Question 5

For what value of displacement the kinetic energy and potential of a simple harmonic oscillation become equal ?

Accepted Answer

x=±2​A​

Answer

x = 0

Answer

x=±A

Answer

x=2A​

Question 6

Two dices are rolled. If both dices have six faces numbered 1, 2,3,5,7 and 11, then the probability that the sum of the numbers on the top faces is less than or equal to 8 is :

Accepted Answer

17/36

Answer

5/12

Answer

4/9

Answer

1/2

Question 7

The equation of the plane which contains the y-axis and passes through the point (1,2,3) is :

Accepted Answer

3x–z=0

Answer

x+3z=0

Answer

3x+z=6

Answer

x+3z=10

Question 8

The value of 4+5+4+5+4+……∞1​1​1​1​ is :

Accepted Answer

2+52​30​

Answer

2+5​4​30​

Answer

5+52​30​

Answer

4+5​4​30​

Question 9

A boy is rolling a 0.5 kg ball on the frictionless floor with the speed of 20 ms−1 . The ball gets deflected by an obstacle on the way. After deflection it moves with 5% of its initial kinetic energy. What is the speed of the ball now?

Accepted Answer

4.47 ms−1

Answer

19.0 ms−1

Answer

1.00 ms−1

Answer

14.41 ms−1

Question 10

Which level of the singly ionized carbon has the same energy as the ground state energy of hydrogen atom ?

Accepted Answer

6

Answer

1

Answer

4

Answer

8

Question 11

With respect to drug-enzyme interaction, identify the wrong statement.

Accepted Answer

Allosteric inhibitor completes with the enzyme's active site

Answer

Non-Competitive inhibitor binds to the allosteric site

Answer

Competitive inhibitor binds to the enzyme's active site

Answer

Allosteric inhibitor changes the enzyme's active site

Question 12

A mass M hangs on a massless rod of length I which rotates at a constant angular frequency. The mass M moves with steady speed in a circular path of constant radius. Assume that the system is in steady circular motion with constant angular velocity ω . The angular momentum of M about point A is LA​ which lies in the positive z direction and the angular momentum of M about point B is LB​ . The correct statement for this system is

Accepted Answer

LA is constant, both in magnitude and direction

Answer

LB​ is constant in direction with varying magnitude

Answer

LA​ and LB​ are both constant magnitude and direction

Answer

LB​ is constant, both in magnitude and direction

Question 13

Reducing smog is a mixture of :

Accepted Answer

Smog, fog and SO2​

Answer

Smog, fog and N2​O3​

Answer

Smog, fog and CH2​=CH−CHO

Answer

Smog, fog and O3​

Question 14

The line 2x−y+1=0 is a tangent to the circle at the point (2,5) and the centre of the circle lies on x−2y=4 . Then, the radius of the circle is :

Accepted Answer

35​

Answer

53​

Answer

54​

Answer

45​

Question 15

The point of intersection and sudden increase in the slope, in the diagram given below, respectively, indicates :

Accepted Answer

ΔG=0 and melting or boiling point of the metal oxide

Answer

ΔG<0 and decomposition of the metal oxide

Answer

ΔG=0 and reduction of the metal oxide

Answer

ΔG>0 and decomposition of the metal oxide