A block of mass M slides down on a rough inclined plane with constant velocity. The angle made by the incline plane with horizontal is . The magnitude of the contact force will be :

Official solved question paper for Joint Entrance Examination (Main). Review all 90 questions, official answer keys, and detailed step-by-step solutions below, or attempt online with timer and negative marking.
A block of mass M slides down on a rough inclined plane with constant velocity. The angle made by the incline plane with horizontal is . The magnitude of the contact force will be :
Two coherent sources of light interfere. The intensity ratio of two sources is . For this interference pattern if the value of is equal to , then will be :
A wire of length 30 cm, stretched between rigid supports, has it's nth and (n + 1)th harmonics at 400 Hz and 450 Hz, respectively. If tension in the string is 2700 N, it's linear mass density is ____________ kg/m.
A spherical soap bubble of radius 3 cm is formed inside another spherical soap bubble of radius 6 cm. If the internal pressure of the smaller bubble of radius 3 cm in the above system is equal to the internal pressure of the another single soap bubble of radius r cm. The value of r is ___________.
Identify the correct statements from the following descriptions of various properties of electromagnetic waves.
(A) In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field.
(B) The energy in electromagnetic wave is divided equally between electric and magnetic fields.
(C) Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave.
(D) The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other.
(E) The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light.
Choose the most appropriate answer from the options given below :
A thin prism of angle and refractive index for yellow light is combined with another prism of angle and . The combination produces no dispersion. The net average deviation produced by the combination is . The value of is ____________.

In the given figure of meter bridge experiment, the balancing length AC corresponding to null deflection of the galvanometer is . The balancing length, if the radius of the wire is doubled, will be ______________ .

A block 'A' takes 2 s to slide down a frictionless incline of 30 and length 'l', kept inside a lift going up with uniform velocity 'v'. If the incline is changed to 45, the time taken by the block, to slide down the incline, will be approximately :
A parallel plate capacitor with width , length and separation between the plates of is connected to a battery of . A dielectric slab of dielectric constant 5 having length , width and thickness is inserted between the plates of parallel plate capacitor. The electrostatic energy of this system will be ____________ J. (Where is the permittivity of free space)
Which statements are correct about degrees of freedom ?
(A) A molecule with n degrees of freedom has n different ways of storing energy.
(B) Each degree of freedom is associated with RT average energy per mole.
(C) A monatomic gas molecule has 1 rotational degree of freedom where as diatomic molecule has 2 rotational degrees of freedom.
(D) has a total of 6 degrees of freedom.
Choose the correct answer from the options given below :
An expression of energy density is given by , where are constants, is displacement, is Boltzmann constant and t is the temperature. The dimensions of will be :
A square wave of the modulating signal is shown in the figure. The carrier wave is given by Volt. The modulation index is :

(A) The drift velocity of electrons decreases with the increase in the temperature of conductor.
(B) The drift velocity is inversely proportional to the area of cross-section of given conductor.
(C) The drift velocity does not depend on the applied potential difference to the conductor.
(D) The drift velocity of electron is inversely proportional to the length of the conductor.
(E) The drift velocity increases with the increase in the temperature of conductor.
Choose the correct answer from the options given below :
A series LCR circuit has and and it is connected to ac voltage of amplitude . At frequency lower than resonant frequency, the amplitude of current will be approximately :
In an experiment to determine the Young's modulus, steel wires of five different lengths , and but of same cross section were taken and curves between extension and load were obtained. The slope (extension/load) of the curves were plotted with the wire length and the following graph is obtained. If the Young's modulus of given steel wires is , then the value of is __________.

A compass needle of oscillation magnetometer oscillates 20 times per minute at a place of . The number of oscillations per minute become 10 at another place of dip. The ratio of the total magnetic field at the two places is :
A cyclotron is used to accelerate protons. If the operating magnetic field is and the radius of the cyclotron 'dees' is , the kinetic energy of the accelerated protons in MeV will be :
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A conducting circular loop is placed in plane in presence of magnetic field in SI unit. If the radius of the loop is , the induced emf in the loop, at time, is . The value of is ___________.
As show in the figure, in steady state, the charge stored in the capacitor is ____________ C.

In case, Carnot engine operates between temperatures and . In case, as shown in the figure, a combination of two engines is used. The efficiency of this combination (in case) will be :

A steel wire of length and a copper wire of length , both of radius are connected end to end. When stretched by a load, the net elongation is found to be . The load applied, in Newton, will be: Given )
The activity of a radioactive material is curie. Its half life is 5 days. The activity will become curie after :
For a constant collector-emitter voltage of , the collector current of a transistor reached to the value of from , whereas base current changed from to value. If transistor is in active state, small signal current gain (current amplification factor) will be :
A solid cylinder length is suspended symmetrically through two massless strings, as shown in the figure. The distance from the initial rest position, the cylinder should be unbinding the strings to achieve a speed of , is ____________ cm. (take g = )

A charge of is to be divided into two. The distance between the two divided charges is constant. The magnitude of the divided charges so that the force between them is maximum, will be :
A body of mass is projected at an angle of with the horizontal. The trajectory of the body is observed to pass through a point . If is the time of flight, then its momentum vector, at time , is _____________.
[Take ]
With reference to the observations in photo-electric effect, identify the correct statements from below :
(A) The square of maximum velocity of photoelectrons varies linearly with frequency of incident light.
(B) The value of saturation current increases on moving the source of light away from the metal surface.
(C) The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (light emitting diode) source of light.
(D) The immediate emission of photo-electrons out of metal surface can not be explained by particle nature of light/electromagnetic waves.
(E) Existence of threshold wavelength can not be explained by wave nature of light/ electromagnetic waves.
Choose the correct answer from the options given below :
Two inclined planes are placed as shown in figure. A block is projected from the Point A of inclined plane AB along its surface with a velocity just sufficient to carry it to the top Point B at a height 10 m. After reaching the Point B the block slides down on inclined plane BC. Time it takes to reach to the point C from point A is s. The value of t is ___________.
(use )

A body of mass is projected with velocity in vertically upward direction from the surface of the earth into space. It is given that is escape velocity and . If air resistance is considered to be negligible, then the maximum height from the centre of earth, to which the body can go, will be :
(R : radius of earth)
The velocity of the bullet becomes one third after it penetrates 4 cm in a wooden block. Assuming that bullet is facing a constant resistance during its motion in the block. The bullet stops completely after travelling at (4 + x) cm inside the block. The value of x is :
Outermost electronic configurations of four elements A, B, C, D are given below :
(A)
(B)
(C)
(D)
The correct order of first ionization enthalpy for them is :
The number of molecule(s) or ion(s) from the following having non-planar structure is ____________.
A gas (Molar mass = 280 ) was burnt in excess in a constant volume calorimeter and during combustion the temperature of calorimeter increased from to . If the heat capacity of calorimeter is and enthalpy of combustion of gas is then amount of gas burnt is _____________ g. (Nearest Integer)
\matrix{ {[A]} & \to & {[B]} \cr {{\mathop{\rm Reactant}\nolimits} } & {} & {{\mathop{\rm Product}\nolimits} } \cr }
If formation of compound follows the first order of kinetics and after 70 minutes the concentration of was found to be half of its initial concentration. Then the rate constant of the reaction is . The value of is ______________. (Nearest Integer)
Match List - I with List - II.
| List - I | List - II | ||
|---|---|---|---|
| (A) | (I) | Dipole moment | |
| (B) | (II) | Bonding molecular orbital | |
| (C) | (III) | Anti-bonding molecular orbital | |
| (D) | (IV) | Bond order |
Choose the correct answer from the options given below :
An element A of group 1 shows similarity to an element B belonging to group 2. If A has maximum hydration enthalpy in group 1 then B is :
For a real gas at temperature and high pressure (99 bar) the value of compressibility factor is 2, so the value of Vander Waal's constant 'b' should be __________ (Nearest integer)
(Given bar )
The correct decreasing order of energy for the orbitals having, following set of quantum numbers :
(A) n = 3, l = 0, m = 0
(B) n = 4, l = 0, m = 0
(C) n = 3, l = 1, m = 0
(D) n = 3, l = 2, m = 1
is :
Given below are two statements :
Statement I : For KI, molar conductivity increases steeply with dilution
Statement II : For carbonic acid, molar conductivity increases slowly with dilution
In the light of the above statements, choose the correct answer from the options given below :
The plot of -metric titration of weak base vs strong acid HCl looks like :




Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Boron is unable to form .
Reason (R) : Size of B is very small.
In the light of the above statements, choose the correct answer from the options given below :
cation gives a prussian blue precipitate on addition of potassium ferrocyanide solution due to the formation of :
Match List - I with List - II.
| List - I (Polymer) |
List - II (Monomer) |
||
|---|---|---|---|
| (A) | Neoprene | (I) | Acrylonitrile |
| (B) | Teflon | (II) | Chloroprene |
| (C) | Acrilan | (III) | Tetrafluoroethene |
| (D) | Natural rubber | (IV) | Isoprene |
Choose the correct answer from the options given below :
Given below are two statements:
Statement I : The non bio-degradable fly ash and slag from steel industry can be used by cement industry.
Statement II : The fuel obtained from plastic waste is lead free.
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 (Mixture) |
List - II (Purification Process) |
||
|---|---|---|---|
| (A) | Chloroform & Aniline | (I) | Steam distillation |
| (B) | Benzoic acid & Napthalene | (II) | Sublimation |
| (C) | Water & Aniline | (III) | Distillation |
| (D) | Napthalene & Sodium chloride | (IV) | Crystallisation |
Choose the correct answer from the options given below :
Among the following ores Bauxite, Siderite, Cuprite, Calamine, Haematite, Kaolinite, Malachite, Magnetite, Sphalerite, Limonite, Cryolite, the number of principal ores if iron is _____________.
Match List - I with Match List - II.
| List - I | List - II | ||
|---|---|---|---|
| (A) | Glucose + HI | (I) | Gluconic acid |
| (B) | Glucose + Br water | (II) | Glucose pentacetate |
| (C) | Glucose + acetic anhydride | (III) | Saccharic acid |
| (D) | Glucose + HNO | (IV) | Hexane |
Choose the correct answer from the options given below:
The structure of A in the given reaction is :





The spin only magnetic moment of the complex present in Fehling's reagent is __________ B.M. (Nearest integer).
The oxidation state of manganese in the product obtained in a reaction of potassium permanganate and hydrogen peroxide in basic medium is ____________.
An organic compound contains nitrogen and chlorine. It dissolves readily in water to give a solution that turns litmus red. Titration of compound with standard base indicates that the molecular weight of is . When a sample of is treated with aq. , a liquid separates which contains but not . Treatment of the obtained liquid with nitrous acid followed by phenol gives orange precipitate. The compound is :




Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Dissolved substances can be removed from a colloidal solution by diffusion through a parchment paper.
Reason (R) : Particles in a true solution cannot pass through parchment paper but the colloidal particles can pass through the parchment paper.
In the light of the above statements, choose the correct answer from the options given below :
Low oxidation state of metals in their complexes are common when ligands :
The normality of in the solution obtained on mixing of with of is _______________ . (Nearest Integer)
When a certain amount of solid A is dissolved in of water at to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is . The number of moles of solute A added is _____________. (Nearest Integer)
Match List - I with List - II.
| List - I | List - II | ||
|---|---|---|---|
| (A) | ![]() |
(I) | Gatterman Koch reaction |
| (B) | C{H_3} - CN\mathrel{\mathop{\kern0pt\longrightarrow}<br>\limits_{{H_3}{O^ + }}^{SnC{l_2}/HCl}} C{H_3} - CHO | (II) | Etard reaction |
| (C) | ![]() |
(III) | Stephen reaction |
| (D) | ![]() |
(IV) | Rosenmund reaction |
Choose the correct answer from the options given below :
In neutral or alkaline solution, oxidises thiosulphate to :
Major product '' of the following reaction sequence is :






In the above reaction, of toluene is converted into benzaldehyde with yield. The amount of benzaldehyde produced is ______________ . (Nearest integer)
Which of the following enhances the lathering property of soap?
Let where [t] denotes the greatest integer . Then is equal to ________________.
Let S be the set of all , for which the complex number is purely imaginary and is purely real. Let . Then is equal to :
A circle passes through the origin and has diameter 4 on the positive -axis. The line gives a chord of circle . Let be the circle with as a diameter. If the tangent to at the point meets the -axis at and -axis at , then is equal to :
Let f be a differentiable function satisfying and . If passes through the point , then is equal to _____________.
If are the roots of the equation
,
then the equation, whose roots are and , is :
The area of the region enclosed by and , is equal to :
Let . Then
For the curve , the value of , at the point , , on C, is equal to ____________.
The equations of the sides and CA of a triangle ABC are and respectively and is its circumcentre. Then which of the following is NOT true?
, where [t] is the greatest integer function, is equal to :
A six faced die is biased such that
a prime numbera composite number.
Let X be a random variable that counts the number of times one gets a perfect square on some throws of this die. If the die is thrown twice, then the mean of X is :
If for , the function is continuous at , then :
Let , , be three non-coplanar vectors such that = 4, = 9 and = , > 0. If , then is equal to __________.
The angle of elevation of the top P of a vertical tower PQ of height 10 from a point A on the horizontal ground is . Let R be a point on AQ and from a point B, vertically above , the angle of elevation of is . If and the area of the trapezium is , then the ordered pair is :
The number of functions , from the set to the set such that , for every , is ___________.
The domain of the function , where [t] is the greatest integer function, is :
Consider a curve in the first quadrant as shown in the figure. Let the area is twice the area . Then the normal to the curve perpendicular to the line does NOT pass through the point.

Consider a matrix , where are three distinct natural numbers.
If , then the number of such 3 - tuples is ____________.
If the line of intersection of the planes and , a makes an angle with the plane , then the direction cosines of the line are :
Let .
Consider
Then,
Let X have a binomial distribution B(n, p) such that the sum and the product of the mean and variance of X are 24 and 128 respectively. If , then k is equal to :
If the length of the latus rectum of a parabola, whose focus is and the tangent at its vertex is , is 16, then is equal to :
Let for the term in the binomial expansion of , in the increasing powers of , to be the greatest for , the least value of is . If is the ratio of the coefficient of to the coefficient of , then is equal to :
If the length of the perpendicular drawn from the point , a on the line is units and is the image of the point P in this line, then is equal to :
If the truth value of the statement is F, then the truth value of which of the following is ?
Let .
If , then is equal to _____________.
Let the sum of an infinite G.P., whose first term is a and the common ratio is r, be 5 . Let the sum of its first five terms be . Then the sum of the first 21 terms of an AP, whose first term is term is and the common difference is , is equal to :
A common tangent to the curves and does not pass through the fourth quadrant. If touches at and at , then is equal to ______________.
is equal to _____________.
A water tank has the shape of a right circular cone with axis vertical and vertex downwards. Its semi-vertical angle is . Water is poured in it at a constant rate of 6 cubic meter per hour. The rate (in square meter per hour), at which the wet curved surface area of the tank is increasing, when the depth of water in the tank is 4 meters, is ______________.