Sound travels in a mixture of two moles of helium and n moles of hydrogen. If rms speed of gas molecules in the mixture is times the speed of sound, then the value of n 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.
Sound travels in a mixture of two moles of helium and n moles of hydrogen. If rms speed of gas molecules in the mixture is times the speed of sound, then the value of n will be :
A block of ice of mass 120 g at temperature 0C is put in 300 g of water at 25C. The x g of ice melts as the temperature of the water reaches 0C. The value of x is _____________.
[Use specific heat capacity of water = 4200 Jkg1K1, Latent heat of ice = 3.5 105 Jkg1]
A current of 15 mA flows in the circuit as shown in figure. The value of potential difference between the points A and B will be:

In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitudes are found to be 6 V and 2 V respectively. The modulation index is :
In a potentiometer arrangement, a cell of emf 1.20 V gives a balance point at 36 cm length of wire. This cell is now replaced by another cell of emf 1.80 V. The difference in balancing length of potentiometer wire in above conditions will be ___________ cm.
An electron with energy 0.1 keV moves at right angle to the earth's magnetic field of 1 104 Wbm2. The frequency of revolution of the electron will be :
(Take mass of electron = 9.0 1031 kg)
A drop of liquid of density is floating half immersed in a liquid of density and surface tension Ncm1. The radius of drop in will be :
(g = 10 ms2)
A ball is projected from the ground with a speed 15 ms1 at an angle with horizontal so that its range and maximum height are equal,
then 'tan ' will be equal to :
The maximum error in the measurement of resistance, current and time for which current flows in an electrical circuit are and respectively. The maximum percentage error in the detection of the dissipated heat will be :
Capacitance of an isolated conducting sphere of radius R1 becomes n times when it is enclosed by a concentric conducting sphere of radius R2 connected to earth. The ratio of their radii is :
Two waves executing simple harmonic motions travelling in the same direction with same amplitude and frequency are superimposed. The resultant amplitude is equal to the times of amplitude of individual motions. The phase difference between the two motions is ___________ (degree).
A convex lens of focal length 20 cm is placed in front of a convex mirror with principal axis coinciding each other. The distance between the lens and mirror is 10 cm. A point object is placed on principal axis at a distance of 60 cm from the convex lens. The image formed by combination coincides the object itself. The focal length of the convex mirror is ____________ cm.
Light wave travelling in air along x-direction is given by . Then, the peak value of magnetic field of wave will be (Given c = 3 108 ms1)
Hydrogen atom from excited state comes to the ground state by emitting a photon of wavelength . The value of principal quantum number '' of the excited state will be : ( Rydberg constant)
The length of a seconds pendulum at a height h = 2R from earth surface will be:
(Given R = Radius of earth and acceleration due to gravity at the surface of earth, g = 2 ms2)
For an object placed at a distance 2.4 m from a lens, a sharp focused image is observed on a screen placed at a distance 12 cm from the lens. A glass plate of refractive index 1.5 and thickness 1 cm is introduced between lens and screen such that the glass plate plane faces parallel to the screen. By what distance should the object be shifted so that a sharp focused image is observed again on the screen?
An object is taken to a height above the surface of earth at a distance R from the centre of the earth. Where radius of earth, R = 6400 km. The percentage decrease in the weight of the object will be :
A particle is moving in a straight line such that its velocity is increasing at 5 ms1 per meter. The acceleration of the particle is _____________ ms2 at a point where its velocity is 20 ms1.
Three identical spheres each of mass M are placed at the corners of a right angled triangle with mutually perpendicular sides equal to 3 m each. Taking point of intersection of mutually perpendicular sides as origin, the magnitude of position vector of centre of mass of the system will be m. The value of x is ____________.
A bag of sand of mass 9.8 kg is suspended by a rope. A bullet of 200 g travelling with speed 10 ms1 gets embedded in it, then loss of kinetic energy will be :
Two parallel plate capacitors of capacity C and 3C are connected in parallel combination and charged to a potential difference 18 V. The battery is then disconnected and the space between the plates of the capacitor of capacity C is completely filled with a material of dielectric constant 9. The final potential difference across the combination of capacitors will be ___________ V.
Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between A and B is __________ .

Let is the efficiency of an engine at and while is the efficiency at and The ratio will be :
The electric current in a circular coil of 2 turns produces a magnetic induction B1 at its centre. The coil is unwound and in rewound into a circular coil of 5 tuns and the same current produces a magnetic induction B2 at its centre. The ratio of is
Magnetic flux (in weber) in a closed circuit of resistance 20 varies with time t(s) at = 8t2 9t + 5. The magnitude of the induced current at t = 0.25 s will be ____________ mA.
Two billiard balls of mass 0.05 kg each moving in opposite directions with 10 ms1 collide and rebound with the same speed. If the time duration of contact is t = 0.005 s, then what is the force exerted on the ball due to each other?
When you walk through a metal detector carrying a metal object in your pocket, it raises an alarm. This phenomenon works on :
is the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its
(i) third permitted energy level to the second level and
(ii) the highest permitted energy level to the second permitted level.
The value of x will be ____________.
The ratio of wavelengths of proton and deuteron accelerated by potential Vp and Vd is 1 : . Then the ratio of Vp to Vd will be :
For a free body diagram shown in the figure, the four forces are applied in the 'x' and 'y' directions. What additional force must be applied and at what angle with positive x-axis so that the net acceleration of body is zero?

The molar conductivity of a conductivity cell filled with 10 moles of 20 mL NaCl solution is and that of 20 moles another identical cell heaving 80 mL NaCl solution is . The conductivities exhibited by these two cells are same. The relationship between and is
Glycosidic linkage between C1 of -glucose and C2 of -fructose is found in
The total number of acidic oxides from the following list is
NO, N2O, B2O3, N2O5, CO, SO3, P4O10
The sum of number of lone pairs of electrons present on the central atoms of XeO3, XeOF4 and XeF6, is ______________
Given below are two statements.
Statement I : Pig iron is obtained by heating cast iron with scrap iron.
Statement II : Pig iron has a relatively lower carbon content than that of cast iron.
In the light of the above statements, choose the correct answer from the options given below.
A sample of 4.5 mg of an unknown monohydric alcohol, R-OH was added to methylmagnesium iodide. A gas is evolved and is collected and its volume measured to be 3.1 mL. The molecular weight of the unknown alcohol is __________ g/mol. [Nearest integer]
The correct order of energy of absorption for the following metal complexes is :
A : [Ni(en)3]2+ , B : [Ni(NH3)6]2+ , C : [Ni(H2O)6]2+
Match List I with List II:
| List I | List II | ||
|---|---|---|---|
| (A) | Sulphate | (I) | Pesticide |
| (B) | Fluoride | (II) | Bending of bones |
| (C) | Nicotine | (III) | Laxative effect |
| (D) | Sodium arsinite | (IV) | Herbicide |
Choose the correct answer from the options given below :
, and are the respective ionization constants for the following reactions (a), (b) and (c).
(a)
(b)
(c)
The relationship between , and is given as :
What is the major product of the following reaction?





Arrange the following in decreasing acidic strength.

For the decomposition of azomethane.
CH3N2CH3(g) CH3CH3(g) + N2(g), a first order reaction, the variation in partial pressure with time at 600 K is given as

The half life of the reaction is __________ 105 s. [Nearest integer]
For micelle formation, which of the following statements are correct?
A. Micelle formation is an exothermic process.
B. Micelle formation is an endothermic process.
C. The entropy change is positive.
D. The entropy change is negative.
56.0 L of nitrogen gas is mixed with excess hydrogen gas and it is found that 20 L of ammonia gas is produced. The volume of unused nitrogen gas is found to be _________ L.
Match List I with List II:
| List I (molecule) |
List II (hybridization ; shape) |
||
|---|---|---|---|
| (A) | XeO | (I) | spd ; linear |
| (B) | XeF | (II) | sp ; pyramidal |
| (C) | XeOF | (III) | spd ; distorted octahedral |
| (D) | XeF | (IV) | spd ; square pyramidal |
Choose the correct answer from the options given below:
High purity (> 99.95%) dihydrogen is obtained by :
The first ionization enthalpies of Be, B, N and O follow the order
A sealed flask with a capacity of 2 dm3 contains 11 g of propane gas. The flask is so weak that it will burst if the pressure becomes 2 MPa. The minimum temperature at which the flask will burst is ___________ C. [Nearest integer]
(Given : R = 8.3 J K1 mol1 , Atomic masses of C and H are 12u and 1u, respectively.) (Assume that propane behaves as an ideal gas.)
When the excited electron of a H atom from n = 5 drops to the ground state, the maximum number of emission lines observed are _____________.
Some drugs bind to a site other than the active site of an enzyme. This site is known as
Match List I with List II :
| List I | List II | ||
|---|---|---|---|
| (A) | Nylon 6, 6 | (I) | Buckets |
| (B) | Low density polythene | (II) | Non-stick utensils |
| (C) | High density polythene | (III) | Bristles of brushes |
| (D) | Teflon | (IV) | Toys |
Choose the correct answer from the options given below :
The correct structure of C is


Two solutions A and B are prepared by dissolving 1 g of non-volatile solutes X and Y, respectively in 1 kg of water. The ratio of depression in freezing points for A and B is found to be 1 : 4. The ratio of molar masses of X and Y is
The total number of monobromo derivatives formed by the alkanes with molecular formula C5H12 is (excluding stereo isomers) __________.
The spin-only magnetic moment value of M3+ ion (in gaseous state) from the pairs Cr3+ / Cr2+, Mn3+ / Mn2+, Fe3+ / Fe2+ and Co3+ / Co2+ that has negative standard electrode potential, is ____________ B.M. [Nearest integer]
Major product of the following reaction is





The correct order of density is :
In base vs. acid titration, at the end point methyl orange is present as
While performing a thermodynamics experiment, a student made the following observations.
HCl + NaOH NaCl + H2O H = 57.3 kJ mol1
CH3COOH + NaOH CH3COONa + H2O H = 55.3 kJ mol1
The enthalpy of ionization of CH3COOH as calculated by the student is _____________ kJ mol1. (nearest integer)
The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance A and substance B from the base line are 3.25 cm, 2.08 cm and 1.05 cm, respectively. The ratio of Rf values of A to B is _____________.
For if the minimum value of is , then a value Question: of is _____________.
Let denote the greatest integer less than or equal to . Then the value of the integral is equal to
is equal to
If and are two events such that and , then is equal to :
The remainder when is divided by 9 is
The number of bijective functions , such that , is ____________.
The sum is equal to
is equal to
If the ellipse meets the line on the -axis and the line on the -axis, then the eccentricity of the ellipse is :
Let a smooth curve be such that the slope of the tangent at any point on it is directly proportional to . If the curve passes through the points and , then is equal to
The tangents at the points and on the parabola meet at the point . Then the area (in unit ) of the triangle is :
The number of real values of , such that the system of linear equations
2x 3y + 5z = 9
x + 3y z = 18
3x y + (2 | |)z = 16
has no solutions, is
Let the point be at a unit distance from each of the two lines , and . If lies below and above , then is equal to :
The sum of the maximum and minimum values of the function in the interval , where is the greatest integer , is ______________.
Let be the solution of the differential equation
.
If for some , then is equal to _____________.
Let the foci of the ellipse and the hyperbola coincide. Then the length of the latus rectum of the hyperbola is :
Let be a quadratic polynomial with leading coefficient 1 such that , and . If the equations and have a common real root, then is equal to ________________.
Let for every n N. Then the sum of all the elements of the set {n N : an (2, 30)} is ____________.
A plane is perpendicular to the two planes and , and passes through the point . If the distance of the plane from the point is , then is equal to :
If the mean deviation about median for the numbers 3, 5, 7, 2k, 12, 16, 21, 24, arranged in the ascending order, is 6 then the median is :
Let and . If , then is equal to _______________.
Let . Define : either or and the sum of all the elements of is a prime number . Then the number of elements in the set is ________________.
Let . If for some
then is equal to ____________.
The shortest distance between the lines and is :
is equal to :
If the circles and , , touch internally at the point , then is equal to ________________.
Let the area enclosed by the x-axis, and the tangent and normal drawn to the curve at the point (2, 3) be A. Then 8A is equal to ______________.
Let and let be a vector such that and . Then the projection of on the vector is :
Let be a twice differentiable function on . If and , then is equal to _______________.
Consider the following statements:
P : Ramu is intelligent.
Q : Ramu is rich.
R : Ramu is not honest.
The negation of the statement "Ramu is intelligent and honest if and only if Ramu is not rich" can be expressed as: