List of top Questions asked in JEE Main

A certain pressure ' $P$ ' is applied to $1$ litre of water and $2$ litre of a liquid separately Water gets compressed to $0.01 \%$ whereas the liquid gets compressed to $0.03 \%$ The ratio of Bulk modulus of water to that of the liquid is $\frac{3}{x}$ The value of $x$ is ________

A light of energy 12.75 eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is $\frac{x}{π} \times 10^{-17} eVs$. The value of x __________ is (use $h=4.14 \times 10^{-15} eVs$, $c=3 \times 108 ms^{-1}$).

In an experiment to find emf of a cell using potentiometer, the length of null point for a cell of emf $15 \,V$ is found to be $60 \,cm$ If this cell is replaced by another cell of emf $E$, the length-of null point increases by $40 \,cm$ The value of $E$ is $\frac{x}{10} V$ The value of $x$ is _______

As shown in the figure, a current of $2 A$ flowing in an equilateral triangle of side $4 \sqrt{3} cm$ The magnetic field at the centroid $O$ of the triangle is

(Neglect the effect of earth's magnetic field)

When the hydrogen ion concentration $\left[ H ^{+}\right]$changes by a factor of $1000$ , the value of $pH$ of the solution_____

Given below are two statements, one is labelled as Assertion $A$ and the other is labelled as Reason $R$
Assertion A: Carbon forms two important oxides - $CO$ and $CO _2 .CO$ is neutral whereas $CO _2$ is acidic in nature
Reason R : $CO _2$ can combine with water in a limited way to form carbonic acid, while $CO$ is sparingly soluble in water
In the light of the above statements, choose the most appropriate answer from the options given below

Match List I with List II

LIST I (Name of polymer)		LIST II (Uses)
A	Glyptal	I	Flexible pipes
B	Neoprene	II	Synthetic wool
C	Acrilan	III	Paints and Lacquers
D	LDP	IV	Gaskets

Choose the correct answer from the options given below:

The equivalent resistance between $A$ and $B$ of the network shown in figure:

A sample of gas at temperature $T$ is adiabatically expanded to double its volume The work done by the gas in the process is (given, $\gamma=\frac{3}{2}$)

A vehicle travels $4 \, km$ with speed of $3\, km / h$ and another $4 \, km$ with speed of $5\, km / h$, then it's average speed is

A. Ammonium salts produce haze in atmosphere
B. Ozone gets produced when atmospheric oxygen reacts with chlorine radicals
C. Polychlorinated biphenyls act as cleansing solvents
D. 'Blue baby' syndrome occurs due to the presence of excess of sulphate ions in water
Choose the correct answer from the options given below:

What is the mass ratio of ethylene glycol $(C _2H _6O_2$, molar mass $62\ g/mol)$ required for making $500\ g$ of $0.25$ molal aqueous solution and $250\ ml$ of $0.25$ molal aqueous solution?

Match List I with List II

LIST I		LIST II
A	Cobalt catalyst	1	(H₂+Cl₂) production
B	Syngas	2	Water gas production
C	Nickel catalyst	3	Coal gasification
D	Brine solution	4	Methanol production

Choose the correct answer from the options given below:

Which of the following frequencies does not belong to FM broadcast?

If a solid sphere of mass $5 kg$ and a disc of mass $4 kg$ have the same radius Then the ratio of moment of inertia of the disc about a tangent in its plane to the moment of inertia of the sphere about its tangent will be $\frac{x}{7}$ The the value of $x$ is ___

A series LCR circuit is connected to an $AC$ source of $220 V , 50 Hz$ The circuit contains a resistance $R =80 \Omega$, an inductor of inductive reactance $X _{ L }=70 \Omega$, and a capacitor of capacitive reactance $X _{ C }=130 \Omega$ The power factor of circuit is $\frac{x}{10}$ The value of $x$ is :

Two cells are connected between points $A$ and $B$ as shown Cell 1 has emf of $12 V$ and internal resistance of $3 \Omega$ Cell 2 has emf of $6 V$ and internal resistance of $6 \Omega$ An external resistor $R$ of $4 \Omega$ is connected across $A$ and $B$ The current flowing through $R$ will be ___A

Match List I with List II:

List I		List II
A.	Attenuation	I.	Combination of a receiver and transmitter
B.	Transducer	II.	Process of retrieval of information from the carrier wave at received
C.	Demodulation	III.	Converts one form of energy into another
D.	Repeater	IV.	Loss of strength of a signal while propagating through a medium

Choose the correct answer from the options given below :

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:

Given below are two statements :
Statement I: Stopping potential in photoelectric effect does not depend on the power of the light source
Statement II: For a given metal, the maximum kinetic energy of the photoelectron depends on the wavelength of the incident light.
In the light of above statements, choose the most appropriate answer from the options given below

An object moves with speed $v_1, v_2$ and $v_3$ along a line segment $AB , BC$ and $C D$ respectively as shown in figure Where $AB = BC$ and $AD =3 AB$, then average speed of the object will be:

A body of mass is taken from earth surface to the height $h$ equal to twice the radius of earth $\left(R_e\right)$ the inerease in potential energy will be:( $g$ = acceleration due to gravity on the surface of Earth)

Among the relations
$S=\left\{(a, b): a, b \in R -\{0\}, 2+\frac{a}{b}>\right\}$
and $T=\left\{(a, b): a, b \in R , a^2-b^2 \in Z\right\}$,

Match List I with List II

List I		List II
A.	Troposphere	I.	Approximate 65-75 km over Earth’s surface
B.	E- Part of Stratosphere	II.	Approximate 300 km over Earth’s surface
C.	F2- Part of Thermosphere	III.	Approximate 10 km over Earth’s surface
D.	D- Part of Stratosphere	IV.	Approximate 100 km over Earth’s surface

Choose the correct answer from the options given below:

Let the mean and standard deviation of marks of class A of $100$ students be respectively $40$ and $\alpha$ (> 0 ), and the mean and standard deviation of marks of class B of $n$ students be respectively $55$ and 30 $-\alpha$. If the mean and variance of the marks of the combined class of $100+ n$ students are respectively $50$ and $350$ , then the sum of variances of classes $A$ and $B$ is :