Practice problems on JEE Mains, JEE Mains 2021 Mar 16 Shift 1

Question 1

Which among the following pairs of Vitamins is stored in our body relatively for longer duration?

Accepted Answer

Vitamin A and Vitamin D

Answer

Thiamine and Vitamin A

Answer

Thiamine and Ascorbic acid

Answer

Ascorbic acid and Vitamin D

Question 2

Which of the following Boolean expression is a tautology ?

Accepted Answer

(p∧q)→(p→q)

Answer

(p∧q)∧(p→q)

Answer

(p∧q)∨(p∨q)

Answer

(p∧q)∨(p→q)

Question 3

The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation:

Accepted Answer

Frequency

Answer

Intensity

Answer

Amplitude

Answer

Phase

Question 4

Given below are two statement : One is labelled as Assertion A and the other is labelled as Reason R :Assertion A: Size of Bk3+ ion is less than Np3+ ion.Reason R: The above is a consequence of the lanthanoid contraction.In the light of the above statements, choose the correct answer from the options given below:

Accepted Answer

A is true but R is false

Answer

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

Answer

A is false but R is true

Answer

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

Question 5

A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figureTwo resistors R1​ and R2​ are connected across the ends of the rails, there is a uniform magnetic field B pointing into the page. An external agent pulls the bar to the left at a constant speed v. The correct statement about the directions of induced currents I1​ and I2​ flowing through R1​ and R2​ respectively is:

Accepted Answer

I1​ is in clockwise direction and I2​ is in anticlockwise direction

Answer

Both I1​ and I2​ are in anticlockwise direction

Answer

Both I1​ and I2​ are in clockwise direction

Answer

I1​ is in anticlockwise direction and I2​ is in clockwise direction

Question 6

The angle of deviation through a prism is minimum when:(A) Incident ray and emergent ray are symmetric to the prims(B) The refracted ray inside the prism becomes parallel to its base(C) Angle of incidence is equal to that of the angle of emergence(D) When angle of emergence is double the angle of incidenceChoose the correct answer from the options given below :

Accepted Answer

Statements (A), (B) and (C) are true

Answer

Only statements (A) and (B) are true

Answer

Statements (B) and (C) are true

Answer

Only statement (D) is true

Question 7

The process that involves the removal of sulphur from the ores is:

Accepted Answer

Roasting

Answer

Smelting

Answer

Leaching

Answer

Refining

Question 8

The pressure acting on a submarine is 3×105 Pa at a certain depth. If the depth is doubled, the percentage increase in the pressure acting on the submarine would be:(Assume that atmospheric pressure is 1×105 Pa density of water is 103 kg m−3, g=10 ms−2 )

Accepted Answer

3200​%

Answer

2005​%

Answer

2003​%

Answer

5200​%

Question 9

The type pollution that gets increased during the day time and in the presence of O3​ is:

Accepted Answer

Oxidising smog

Answer

Global warming

Answer

Acid rain

Answer

Reducing smog

Question 10

Given below are two statements :Statement I : The E0 value for Ce4+/Ce3+ is +1.74 V .Statement II : Ce is more stable in Ce4+ state than Ce3+ state.In the light of the above statements, choose the most appropriate answer from the options given below:

Accepted Answer

Statement I is correct but statement II is incorrect

Answer

Both statement I and statement II are correct

Answer

Statement I is incorrect but statement II is correct

Answer

Both statement I and statement II are incorrect

Question 11

Which of the following is Lindlar catalyst?

Accepted Answer

Partially deactivated palladised charcoal

Answer

Cold dilute solution of KMnO4​

Answer

Zinc chloride and HCl

Answer

Sodium and Liquid NH3​

Question 12

The locus of the midpoints of the chord of the circle, x2+y2=25 which is tangent to the hyperbola 9x2​−16y2​=1 is :

Accepted Answer

(x2+y2)2−9x2+16y2=0

Answer

(x2+y2)2−16x2+9y2=0

Answer

(x2+y2)2−9x2+144y2=0

Answer

(x2+y2)2−9x2−16y2=0

Question 13

In chromatography technique, the purification of compound is independent of :

Accepted Answer

Physical state of the pure compound

Answer

Length of the column or TLC plate

Answer

Mobility or flow of solvent system

Answer

Solubility of the compound

Question 14

A 25 m long, antenna is mounted on an antenna tower. The height of the antenna tower is 75 m . The wavelength (in meter) of the signal transmitted by the antenna would be:

Accepted Answer

100

Answer

300

Answer

400

Answer

200

Question 15

In thermodynamics, heat and work are:

Accepted Answer

Path functions

Answer

Extensive thermodynamic state variables

Answer

Point functions

Answer

Intensive thermodynamic state variables