List of top Questions asked in JEE Main

There are 5 black and 3 white balls in the bag. A die is rolled, we need to pick the number of balls appearing on the die. The probability that the balls are white is?

The mean and standard deviation of 10 observations are 20 and 8 respectively. Later on, it was observed that one observation was recorded as 50 instead of 40. Then the correct variance is:

The total number of three-digit numbers, divisible by 3, which can be formed using the digits 1,3,5,8, if repetition of digits is allowed, is

Let the determinant of a square matrix A of order $ m $ be $ m - n $, where $ m $ and $ n $ satisfy $ 4m + n = 22 $ and $ 17m + 4n = 93 $. If $ \text{det} (n \, \text{adj}(\text{adj}(mA))) = 3^a 5^b 6^c $, then $ a + b + c $ is equal to:

Orthocentre of triangle having vertices as A (1,2), B(3,-4), C(0,6) is

Match List I with List II:

List I		List II
A	AC generator	i	Presence of both L and C
B	Transformer	ii	Electromagnetic Induction
C	Resonance phenomenon to occur	iii	Quality factor
D	Sharpness of resonance	iv	Mutual Induction

Choose the correct answer from the options given below:

Match List I with List II:

List I		List II
A	Microwaves	i	Radioactive decay of the nucleus
B	Gamma waves	ii	Rapid acceleration and deceleration of electrons in aerials
C	Radio waves	iii	Inner shell electrons
D	X - rays	iv	Klystron valve

Choose the correct answer from the options given below:

Given below are two statements:
Statement I : Acceleration due to gravity is different at different places on the surface of earth
Statement II : Acceleration due to gravity increases as we go down below the earth's surface
In the light of the above statements, choose the correct answer from the options given below

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: In an Ellingham diagram, the oxidation of carbon to carbon monoxide shows a negative slope with respect to temperature
Reason R: CO tends to get decomposed at higher temperature
In the light of the above statements, choose the correct answer from the options given below

Let $S$ denote the set of all real values of $\lambda$ such that the system of equations
$ \lambda x+y+z=1 $
$x+\lambda y+z=1 $
$x+y+\lambda z=1$
is inconsistent, then $\displaystyle \sum_{\lambda \in S}\left(|\lambda|^2+|\lambda|\right)$ is equal to

The negation of the expression $q \vee((\sim q) \wedge p)$ is equivalent to

If the velocity of light $c$, universal gravitational constant $G$ and Planck's constant $h$ are chosen as fundamental quantities The dimensions of mass in the new system is :

A Carnot engine operating between two reservoirs has efficiency $\frac{1}{3}$ When the temperature of cold reservoir raised by $x$, its efficiency decreases to $\frac{1}{6}$ The value of $x$, if the temperature of hot reservoir is $99^{\circ} C$, will be :

A coil is placed in magnetic field such that plane of coil is perpendicular to the direction of magnetic field. The magnetic flux through a coil can be changed :
A. By changing the magnitude of the magnetic field within the coil
B. By changing the area of coil within the magnetic field
C. By changing the angle between the direction of magnetic field and the plane of the coil
D. By reversing the magnetic field direction abruptly without changing its magnitude.
Choose the most appropriate answer from the options given below :

In an amplitude modulation, a modulating signal having amplitude of $X V$ is superimposed with a carrier signal of amplitude $Y V$ in first case. Then, in second case, the same modulating signal is superimposed with different carrier signal of amplitude $2 YV$. The ratio of modulation index in the two cases respectively will be :

Choose the correct statement about Zener diode :

As shown in the figure, a long straight conductor with semi-circular are of radius $\frac{\pi}{10} m$ is carrying current $I =3 A$. The magnitude of the magnetic field at the center $O$ of the arc is :(The permeability of the vacuum $=4 \pi \times 10^{-7} NA ^{-2}$ )

For a body projected at an angle with the horizontal from the ground, choose the correct statement.

Given below are two statements : One is labelled as Assertion $A$ and the other is labelled as Reason R
Assertion A : For measuring the potential difference across a resistance of $600 \Omega$, the voltmeter with resistance $1000 \Omega$ will be preferred over voltmeter with resistance $4000 \Omega$.
Reason R : Voltmeter with higher resistance will draw smaller current than voltmeter with lower resistance.
In the light of the above statements, choose the most appropriate answer from the options given below

The starting material for convenient preparation of deuterated hydrogen peroxide $\left(D_2 O _2\right)$ in laboratory is :