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COMEDK Mock Test - 4 - JEE MCQ


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30 Questions MCQ Test COMEDK Mock Test Series - COMEDK Mock Test - 4

COMEDK Mock Test - 4 for JEE 2024 is part of COMEDK Mock Test Series preparation. The COMEDK Mock Test - 4 questions and answers have been prepared according to the JEE exam syllabus.The COMEDK Mock Test - 4 MCQs are made for JEE 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for COMEDK Mock Test - 4 below.
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COMEDK Mock Test - 4 - Question 1

A Carnot engine takes 5000 kcal of heat from a reservoir at 727°C and gives heat to a sink at 127°C. The work done by the engine is

Detailed Solution for COMEDK Mock Test - 4 - Question 1


⇒ W = 0.6Q = 3000 kcal = 12.6 × 106 J

COMEDK Mock Test - 4 - Question 2

Identify the pair of physical quantities that have same dimensions.

Detailed Solution for COMEDK Mock Test - 4 - Question 2


Decay constant λ has dimensions of [T-1] because of the relation dN/dt = -λN.
⇒ Velocity gradient and decay constant have same dimensions.

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COMEDK Mock Test - 4 - Question 3

A radioactive material decays by simultaneous emissions of two particles with half lives of 1400 years and 700 years, respectively. What will be the time after which one third of the material remains? (Take In 3 = 1.1)

Detailed Solution for COMEDK Mock Test - 4 - Question 3


Given:


Now, let the initial number of radioactive nuclei be N0.

COMEDK Mock Test - 4 - Question 4

A plane electromagnetic wave travels in a medium of relative permeability 1.61 and relative permittivity 6.44. If magnitude of magnetic intensity is 4.5 × 10-2 Am-1 at a point, what will be the approximate magnitude of electric field intensity at that point?
(Given: Permeability of free space  speed of light in vacuum c = 3 × 108 ms-1)

Detailed Solution for COMEDK Mock Test - 4 - Question 4

H = 4.5 × 10-2
So, B = μ0μH
Thus, E =  c/nB (where n ⇒ refractive index)
So, 

E = 8.48

COMEDK Mock Test - 4 - Question 5

An elastic wire is stretched by 3 cm from its natural length and its potential energy is V. If the wire is stretched by 6 cm from its natural length, its potential energy will be

Detailed Solution for COMEDK Mock Test - 4 - Question 5
The potential energy of an elastic wire, U ∝ x2

∴ U2 = 4U1 = 4V

COMEDK Mock Test - 4 - Question 6

The product of energy and time is called action. The dimensional formula for action is same as that for

Detailed Solution for COMEDK Mock Test - 4 - Question 6

Both are different from each other.
Energy × Time=(M1L2T−2)×(T1)=M1L2T−1
Force × Velocity=(M1L1T−2)×(L1T−1)=M1L2T−3
Impulse × distance=(M1L1T−1)×(L1)=M1L2T−1
Power=M1L2T−3
Angular Energy=M1L1T−2

COMEDK Mock Test - 4 - Question 7

The displacement of a damped harmonic oscillator is given by:
x(t) = e-0.1t cos (10πt + φ). Hence, t is in seconds.

The time taken for its amplitude of vibration to drop to half of its initial value is close to:

Detailed Solution for COMEDK Mock Test - 4 - Question 7

COMEDK Mock Test - 4 - Question 8

3 point particles of masses 1.0 kg, 1.5 kg and 2.5 kg are placed at 3 corners of a right angle triangle of sides 4.0 cm, 3.0 cm and 5.0 cm as shown in the figure. The centre of mass of the system is at a point

Detailed Solution for COMEDK Mock Test - 4 - Question 8


Let m1 = 1 kg, m2 = 1.5 kg and m3 = 2.5 kg
x1 = 0, x2 = 3, x3 = 0 and y1 = 0, y2 = 0, y3 = 4

Let point A be the origin and mass m1 = 1.0 kg be at origin.

So, centre of mass of the system is at (0.9, 2).
So, 0.9 cm right and 2.0 cm above 1 kg mass

COMEDK Mock Test - 4 - Question 9

Trioxane is trimer of

COMEDK Mock Test - 4 - Question 10

Which of the following gives iodoform on heating with a solution of l2 containing Na2CO3 ?

COMEDK Mock Test - 4 - Question 11

The protein which maintains blood sugar level is

COMEDK Mock Test - 4 - Question 12

Which one of the following proteins transports oxygen in the blood stream?

COMEDK Mock Test - 4 - Question 13

For the melting of a solid at 250C, the fusion process requires energy equivalent to 2906 Joules to be added to system considering the process to be reversible at fusion point, the entropy change of the process is

COMEDK Mock Test - 4 - Question 14

The rate, at which a substance reacts at constant temperature, depends upon its

COMEDK Mock Test - 4 - Question 15

Heat of combustion of carbon is 96k cal mol-1. When some quantity of carbon is burnt in oxygen, 48 k cal of heat is liberated. What is the volume (in lit) of oxygen at STP reacted with this carbon?

Detailed Solution for COMEDK Mock Test - 4 - Question 15



∵ 96 k cal heat is produced by 1 mol of carbon.
∴ 48 k cal heat is produced by 0.5 mol of carbon.
As 1 mol carbon reacts with 1 mol of oxygen, which has 22.4 litre volume at NTP.
∴ The volume of O2 at NTP reacts with 0.5 mol carbon = 22.4/2 = 11.2 litre.

COMEDK Mock Test - 4 - Question 16

Name of the following compound is 

COMEDK Mock Test - 4 - Question 17

Dye test can be used to distinguish between

COMEDK Mock Test - 4 - Question 18

Absolute ethyl alcohol can be converted to diethyl ether by heating it to 410 K in the presence of

COMEDK Mock Test - 4 - Question 19

Oxytocin is

COMEDK Mock Test - 4 - Question 20

Self condensation of two moles of ethyl acetate in presence of sodium ethoxide yields

COMEDK Mock Test - 4 - Question 21

An electrolyte

COMEDK Mock Test - 4 - Question 22

The pH of aqueous KCl solution is 7.0. This solution was electrolysed for a few seconds using Pt electrodes. Which of the following is correct?

COMEDK Mock Test - 4 - Question 23

Which of the following reacts rapidly with oxygen in air at ordinary temperature

COMEDK Mock Test - 4 - Question 24

If then dy/dx is equal to:

Detailed Solution for COMEDK Mock Test - 4 - Question 24

On differentiating w.r.t. x, 
we get

COMEDK Mock Test - 4 - Question 25

Period of 

Detailed Solution for COMEDK Mock Test - 4 - Question 25

As   is not a linear function of x i.e., of the type ax+b, the given function is not periodic.

COMEDK Mock Test - 4 - Question 26

If  then sin  4θ is equal to

Detailed Solution for COMEDK Mock Test - 4 - Question 26

COMEDK Mock Test - 4 - Question 27

The period of the function f(x) = |sin x| + |cos x| is

Detailed Solution for COMEDK Mock Test - 4 - Question 27

COMEDK Mock Test - 4 - Question 28

COMEDK Mock Test - 4 - Question 29

For solving dy/dx=4x+y+1 suitable substitution is

COMEDK Mock Test - 4 - Question 30

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