Which of the following relations is true for two unit vector and making an angle to each other?

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.
Which of the following relations is true for two unit vector and making an angle to each other?
If force acts on a particle position vector then, the torque about the origin will be :
The two light beams having intensities I and 9I interfere to produce a fringe pattern on a screen. The phase difference between the beams is /2 at point P and at point Q. Then the difference between the resultant intensities at P and Q will be :
Given below are two statements :
Statement I : Davisson-Germer experiment establishes the wave nature of electrons.
Statement II : If electrons have wave nature, they can interfere and show diffraction.
In the light of the above statements choose the correct answer from the option given below :
The difference of speed of light in the two media A and B (vA vB) is 2.6 107 m/s. If the refractive index of medium B is 1.47, then the ratio of refractive index of medium B to medium A is : (Given : speed of light in vacuum c = 3 108 ms1)
A uniform chain of 6 m length is placed on a table such that a part of its length is hanging over the edge of the table. The system is at rest. The co-efficient of static friction between the chain and the surface of the table is 0.5, the maximum length of the chain hanging from the table is ___________ m.
The electric field in an electromagnetic wave is given by E = 56.5 sin (t x/c) NC1. Find the intensity of the wave if it is propagating along x-axis in the free space.
(Given : 0 = 8.85 1012C2N1m2)
A long straight wire with a circular cross-section having radius R, is carrying a steady current I. The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance r (r < R) from its centre will be :
If wattless current flows in the AC circuit, then the circuit is :
In the figure, a very large plane sheet of positive charge is shown. P1 and P2 are two points at distance l and 2l from the charge distribution. If is the surface charge density, then the magnitude of electric fields E1 and E2 at P1 and P2 respectively are :

If , then the relative error in Z will be :
The height of any point P above the surface of earth is equal to diameter of earth. The value of acceleration due to gravity at point P will be : (Given g = acceleration due to gravity at the surface of earth).
A light wave travelling linearly in a medium of dielectric constant 4, incidents on the horizontal interface separating medium with air. The angle of incidence for which the total intensity of incident wave will be reflected back into the same medium will be :
(Given : relative permeability of medium r = 1)
The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because :
is a vector quantity such that = non-zero constant. Which of the following expression is true for ?
The terminal velocity (vt) of the spherical rain drop depends on the radius (r) of the spherical rain drop as :
A signal of 100 THz frequency can be transmitted with maximum efficiency by :
Match List-I with List-II.
| List - I | List -II | ||
|---|---|---|---|
| (A) | AC generator | (I) | Detects the presence of current in the circuit |
| (B) | Galvanometer | (II) | Converts mechanical energy into electrical energy |
| (C) | Transformer | (III) | Works on the principle of resonance in AC circuit |
| (D) | Metal detector | (IV) | Changes an alternating voltage for smaller or greater value |
Choose the correct answer from the options given below :
The ratio for the speed of the electron in the 3rd orbit of He+ to the speed of the electron in the 3rd orbit of hydrogen atom will be :
The equivalent capacitance between points A and B in below shown figure will be __________ F.

A 0.5 kg block moving at a speed of 12 ms1 compresses a spring through a distance 30 cm when its speed is halved. The spring constant of the spring will be _______________ Nm1.
The total current supplied to the circuit as shown in figure by the 5 V battery is ____________ A.

A resistor develops 300 J of thermal energy in 15 s, when a current of 2 A is passed through it. If the current increases to 3 A, the energy developed in 10 s is ____________ J.
A force on an object of mass 100 g is N. The position of that object at t = 2 s is m after starting from rest. The value of will be ___________.
The relation between root mean square speed (vrms) and most probable sped (vp) for the molar mass M of oxygen gas molecule at the temperature of 300 K will be :
A teacher in his physics laboratory allotted an experiment to determine the resistance (G) of a galvanometer. Students took the observations for deflection in the galvanometer. Which of the below is true for measuring value of G?
The first overtone frequency of an open organ pipe is equal to the fundamental frequency of a closed organ pipe. If the length of the closed organ pipe is 20 cm. The length of the open organ pipe is _____________ cm.
The current in a coil of self inductance 2.0 H is increasing according to I = 2 sin(t2) A. The amount of energy spent during the period when current changes from 0 to 2 A is ____________ J.
A steam engine intakes 50 g of steam at 100C per minute and cools it down to 20C. If latent heat of vaporization of steam is 540 cal g1, then the heat rejected by the steam engine per minute is __________ 103 cal.
(Given : specific heat capacity of water : 1 cal g1 C1)
The velocity of upper layer of water in a river is 36 kmh1. Shearing stress between horizontal layers of water is 103 Nm2. Depth of the river is __________ m. (Co-efficient of viscosity of water is 102 Pa.s)
The major product in the reaction

1 L aqueous solution of H2SO4 contains 0.02 m mol H2SO4. 50% of this solution is diluted with deionized water to give 1 L solution (A). In solution (A), 0.01 m mol of H2SO4 are added. Total m mols of H2SO4 in the final solution is ___________ 103 m mols.
Incorrect statement for Tyndall effect is :
The standard free energy change (G) for 50% dissociation of N2O4 into NO2 at 27C and 1 atm pressure is x J mol1. The value of x is ___________. (Nearest Integer)
[Given : R = 8.31 J K1 mol1, log 1.33 = 0.1239 ln 10 = 2.3]
Number of electron deficient molecules among the following
PH3, B2H6, CCl4, NH3, LiH and BCl3 is
Cerium (IV) has a noble gas configuration. Which of the following is correct statement about it?
The pair, in which ions are isoelectronic with AI3+ is :
In a cell, the following reactions take place
\matrix{ {F{e^{2 + }} \to F{e^{3 + }} + {e^ - }} & {E_{F{e^{3 + }}/F{e^{2 + }}}^o = 0.77\,V} \cr {2{I^ - } \to {I_2} + 2{e^ - }} & {E_{{I_2}/{I^ - }}^o = 0.54\,V} \cr }
The standard electrode potential for the spontaneous reaction in the cell is x 102 V 298 K. The value of x is ____________. (Nearest Integer)
Using very little soap while washing clothes, does not serve the purpose of cleaning of clothes, because :
White precipitate of AgCl dissolves in aqueous ammonia solution due to formation of :
In the following structures, which on is having staggered conformation with maximum dihedral angle?




Bonding in which of the following diatomic molecule(s) become(s) stronger, on the basis of MO Theory, by removal of an electron?
(A) NO
(B) N2
(C) O2
(D) C2
(E) B2
Choose the most appropriate answer from the options given below :
The intermediate X, in the reaction :





In the following reaction :

The compounds A and B respectively are :




For a given chemical reaction
1A + 2B 3C + 4D
Concentration of C changes from 10 mmol dm3 to 20 mmol dm3 in 10 seconds. Rate of appearance of D is 1.5 times the rate of disappearance of B which is twice the rate of disappearance A. The rate of appearance of D has been experimentally determined to be 9 mmol dm3 s1. Therefore, the rate of reaction is _____________ mmol dm3 s1. (Nearest Integer)
Number of grams of bromine that will completely react with 5.0 g of pent-1-ene is ___________ 102 g. (Atomic mass of Br = 80 g/mol) [Nearest Integer]
Which one of the following is an example of artificial sweetner?
The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is x 108 m. The value of x is ___________. (Nearest Integer).
(Given : Energy of the electron in the first shell of the hydrogen atom is 2.2 1018 J ; h = 6.63 1034 Js and c = 3 108 ms1)
Phenol on reaction with dilute nitric acid, gives two products. Which method will be most efficient for large scale separation?
The distance between Na+ and Cl ions in solid NaCl of density 43.1 g cm3 is _______________ 1010 m. (Nearest Integer)
(Given : NA = 6.02 1023 mol1)
The IUPAC name of ethylidene chloride is :
The product formed in the following reaction.





Which one of the following alkaline earth metal ions has the highest ionic mobility in its aqueous solution?
The number of N atoms in 681 g of C7H5N3O6 is x 1021. The value of x is (NA = 6.02 1023 mol1) (Nearest Integer)
The eutrophication of water body results in :
The standard entropy change for the reaction
4Fe(s) + 3O2(g) 2Fe2O3(s) is 550 J K1 at 298 K.
[Given : The standard enthalpy change for the reaction is 165 kJ mol1]. The temperature in K at which the reaction attains equilibrium is _____________. (Nearest Integer)
Among the following, which is the strongest oxidizing agent?
Leaching of gold with dilute aqueous solution of NaCN in presence of oxygen gives complex [A], which on reaction with zinc forms the elemental gold and another complex [B]. [A] and [B], respectively are :
If [Cu(H2O)4]2+ absorbs a light of wavelength 600 nm for d-d transition, then the value of octahedral crystal field splitting energy for [Cu(H2O)6]2+ will be ____________ 1021 J. [Nearest Integer]
(Given : h = 6.63 1034 Js and c = 3.08 108 ms1)
The reaction of
with bromine and KOH gives RNH2 as the end product. Which one of the following is the intermediate product formed in this reation?


Let f : N R be a function such that for natural numbers x and y. If f(1) = 2, then the value of for which
holds, is :
Let A be a 3 3 real matrix such that
and .
If and I is an identity matrix of order 3, then the system has :
Let Q be the mirror image of the point P(1, 0, 1) with respect to the plane S : x + y + z = 5. If a line L passing through (1, 1, 1), parallel to the line PQ meets the plane S at R, then QR2 is equal to :
Let the abscissae of the two points P and Q be the roots of and the ordinates of P and Q be the roots of . If the equation of the circle described on PQ as diameter is , then is equal to __________.
Let be the angle between the vectors and , where and . Then is equal to __________.
The number of 3-digit odd numbers, whose sum of digits is a multiple of 7, is _____________.
Let be a differentiable function such that
, for all x > 0, where c is an arbitrary constant. Then :
The value of is equal to:
The number of values of x in the interval for which
holds, is ____________.
Let f : R R be defined as . If g(x) is a function such that , then g'(63) is equal to ________________.
If the solution curve of the differential equation , which passes through the point (1, 1) and intersects the line at the point , then value of is equal to :
Let A = \left[ {\matrix{ 0 & { - 2} \cr 2 & 0 \cr } } \right]. If M and N are two matrices given by and then MN2 is :
For a natural number n, let . Then, the value of is ___________.
Let and be two functions defined by and . Then, for which of the following range of , the inequality holds ?
Let a, b and c be the length of sides of a triangle ABC such that . If r and R are the radius of incircle and radius of circumcircle of the triangle ABC, respectively, then the value of is equal to :
Let , be a vector which makes equal angles with the coordinate axes OX, OY and OZ. Also, let the projection of on the vector be 7. Let be a vector obtained by rotating with 90. If , and x-axis are coplanar, then projection of a vector on is equal to:
Let be a function defined by
. If the function , then the greatest integer less than or equal to g(1) is ____________.
Let E1 and E2 be two events such that the conditional probabilities , and . Then :
If and , are two common tangents of circle and parabola y2 = x, then the value of is equal to :
Consider the following two propositions:
If the proposition is evaluated as FALSE, then :
Let A be a 3 3 matrix having entries from the set {1, 0, 1}. The number of all such matrices A having sum of all the entries equal to 5, is ___________.
The greatest integer less than or equal to the sum of first 100 terms of the sequence ...... is equal to ___________.
Let a circle C in complex plane pass through the points , and . If is a point on C such that the line through z and z1 is perpendicular to the line through z2 and z3, then is equal to :
Let be the solution of the differential equation , with . Then, the point for the curve is :
Let the lines
,
intersect at the point S. If a plane ax + by z + d = 0 passes through S and is parallel to both the lines L1 and L2, then the value of a + b + d is equal to ____________.
Let f(x) be a polynomial function such that . Then, the value of is equal to:
If , then the remainder when K is divided by 6 is :
Let , be a conic. Let S be the focus and B be the point on the axis of the conic such that , where A is any point on the conic. If k is the ordinate of the centroid of the SAB, then is equal to :
Let Cr denote the binomial coefficient of xr in the expansion of . If for , R, ....... upto 10 terms then the value of + is equal to ___________.