List of top Questions asked in JEE Main

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): In expensive scientific instruments, silica gel is kept in watch-glasses or in semipermeable membrane bags.
Reason (R): Silica gel adsorbs moisture from air via adsorption, thus protects the instrument from water corrosion (rusting) and/or prevents malfunctioning.
In the light of the above statements, choose the correct answer from the options given below:

In the wet tests for identification of various cations by precipitation, which transition element cation doesn’t belong to group IV in qualitative inorganic analysis?

Lithium aluminium hydride can be prepared from the reaction of:

Let S = {1, 2, 3, 4, 5}
if f : S → P(S), where P(S) is power set of S. Then number of one-one functions f can be made is

A straight line cuts off the intercepts OA = a and OB = b on the positive directions of the x-axis and y-axis, respectively. If the perpendicular from the origin O to this line makes an angle of $\frac{\pi}{6}$ with the positive direction of the y-axis and the area of △OAB is $\frac{98\sqrt{3}}{3},$ then a² − b² is equal to:

If [t] denotes the greatest integer $≤ 1$, then the value of $3\frac{(e - 1)^2}{e}$ is:

The time taken by an object to slide down 45° rough inclined plane is n times as it takes to slide down a perfectly smooth 45° incline plane. The coefficient of kinetic friction between the object and the incline plane is:

Substance A has atomic mass number 16 and half-life of 1 day. Another substance 𝐵 has atomic mass number 32 and half life of $\frac1{ 2}$ day. If both 𝐴 and 𝐵 simultaneously start undergo radio activity at the same time with initial mass 320 g each, how many total atoms of A and B combined would be left after 2 days.

Given below are two statements:
Statement I: Electromagnetic waves are not deflected by electric and magnetic field.
Statement II: The amplitude of electric field and the magnetic field in electromagnetic waves are related to each other as $E_0 = \sqrt{\frac{\mu_0}{E_0}}B_0$.
In the light of the above statements, choose the correct answer from the options given below:

The electric current in a circular coil of four turns produces a magnetic induction 32 T at its centre. The coil is unwound and is rewound into a circular coil of single turn, the magnetic induction at the centre of the coil by the same current will be :

The time period of a satellite of earth is 24 hours. If the separation between the earth and the satellite is decreased to one fourth of the previous value, then its new time period will become.

With the help of potentiometer, we can determine the value of emf of a given cell. The sensitivity of the potentiometer is
(A) directly proportional to the length of the potentiometer wire
(B) directly proportional to the potential gradient of the wire
(C) inversely proportional to the potential gradient of the wire
(D) inversely proportional to the length of the potentiometer wire
Choose the correct option for the above statements:

For the given figures, choose the correct options:

The rms current in circuit (b) can never be larger than that in (a)

The equation of a circle is given by $𝑥^2+𝑦^2=𝑎^2$, where 𝑎 is the radius. If the equation is modified to change the origin other than (0,0) then. find out the correct dimensions of A and B in a new equation : $(𝑥−𝐴𝑡)^2+(𝑦−𝑡 𝐵 )^2 =𝑎^2$. The dimensions of 𝑡 is given as $[T^{−1}]$.

A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option)

A force acts for 20 s on a body of mass 20 kg, starting from rest, after which the force ceases and then body describes 50 m in the next 10 s. The value of force will be:

Identify the correct statements from the following:
A. Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket is negative.
B. Work done by gravitational force in lifting a bucket out of a well by a rope tied to the bucket is negative.
C. Work done by friction on a body sliding down an inclined plane is positive.
D. Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity in zero.
E. Work done by the air resistance on an oscillating pendulum in negative.
Choose the correct answer from the options given below:

Match List I and List II

List II	List II
A. Osmosis	I. Solvent molecules pass through semi permeable membrane towards solvent side.
B. Reverse osmosis	II. Movement of charged colloidal particles under the influence of applied electric potential towards oppositely charged electrodes.
C. Electro osmosis	III. Solvent molecules pass through semi permeable membrane towards solution side.
D. Electrophoresis	IV. Dispersion medium moves in an electric field.

Choose the correct answer from the options given below :

The concentration of dissolved Oxygen in water for growth of fish should be more than 𝑋 ppm and Biochemical Oxygen Demand in clean water should be less than 𝑌 ppm. X and Y in ppm are, respectively.

The major component of which of the following ore is sulphide based mineral?

A solution of $C_rO_5 $ in amyl alcohol has a _____ colour.

Which of the following relations are correct?
(A) $ΔU=q+pΔV$
(B) $ΔG=ΔH−TΔS$
(C) $ΔS=\frac{𝑞_{𝑟𝑒𝑣}}{𝑇}$
(D) $ΔH=ΔU−ΔnRT$
Choose the most appropriate answer from the options given below:

Correct order of spin only magnetic moment of the following complex ions is:
(Given At.no. Fe: 26, Co:27)

When a hydrocarbon A undergoes combustion in the presence of air, it requirs 9.5 equivalents of oxygen and produces 3 equivalents of water. What is the molecular formula of A?

Following tetrapeptide can be represented as

(F, L, D, Y, I, Q, P are one letter codes for amino acids)