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A d.c. motor having an armature of resistance 2 Ω is designed to operate at 220 V mains. At full speed, it develops a back e.m.f. of 210 V. When the motor is running at full speed, the current in the armature is
When motor is running at full speed the electric current is given by:
A solenoid has an inductance of 60 henrys and a resistance of 30 ohms. If it is connected to a 100 volt battery, how long will it take for the current to reach e1/e=63.2% of its final value
A dipole of dipole moment p̅ is placed in uniform electric field E̅, then torque acting on it is given by
What fraction of a radioactive material will get disintegrated in a period of two halflives
What percentage of original radioactive atoms is left after five half lives ?
Photons of energy 5.5eV fall on the surface of the metal emitting photoelectrons of maximum kinetic energy 4.0eV. The stopping potential required for these electrons are :
The angular speed of an engine wheel making 90 revolutions per minute is
An electric dipole is placed along the Xaxis at the origin O. A point P is at a distance of 20 cm from this origin such that OP makes an angle π/3 with the X axis. If electric field at P makes an angle θ with Xaxis, the value of θ is
A man of mass 60 kg. records his wt. on a weighing machine placed inside a lift. The ratio of wts. of man recorded when lift is ascending up with a uniform speed of 2 m/s to when it is descending down with a uniform speed of 4 m/s will be
A boat of mass 40 kg is at rest. If a dog of mass 4 kg moves in the boat with a velocity of 10 m/s, then velocity of a boat will be
According to law of conservation of momentum
(m_{d} + m_{b})υ_{b} = m_{d} υ_{d}
⇒ 44 υ_{b} = 4 x 10
⇒ υ_{b} = 1 m/s
A microammeter has a resistance of 100 Ω and full scale range of 50 μ A. It can be used as a voltmeter or as a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combination
Spherical balls of radius R are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is
The symbolic representation of four logic gates are given below:
The logic symbols for OR, NOT and NAND gates are respectively:
The size of nucleus of an atom of mass number A is proportional to
A ball is moving to and fro about the lowest point A of a smooth hemisphrical bowl. If it is able to rise up to a height of 20 cm on either side of A, its speed at A must be (Take = 10 m/s^{2.} mass of the body 5 g)
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer
Assertion(A): By the study of positive rays, Thomson discovered the existence of isotopes.
Reason(R): Thomson obtained two parabolas for neon gas whose atomic mass is 20.2 .
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer
Assertion(A): When a massive projectile collides with a lighter stationary target then maximum speed of target is twice that of projectile.
Reason(R): It is explained by the momentum and energy conservation.
Two rings of the same radius and mass are placed such that their centres are at a common point and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the centre and perpendicular to the plane of one of the ring is (mass = and radius = r)
A process in which volume remains constant is called
The H α line is the first member of the Balmer series of the hydrogen spectrum and it occurs due to the transition of the electron from the 3^{rd} orbit to the 2^{nd}orbit. If its wave length is λ , the wave length of the last member of the Balmer series will be
If the charge on a capacitor is increased by 2 coulomb, the energy stored in it increases by 21%. The original charge on the capacitor is
A particle is moving on a circular path with constant speed, then its acceleration will be
At what temperature will the resistance of a copper wire be three times its value at 0ºC? (Given Temperature coefficient of resistance for copper = 4x10⁻^{3}ºC⁻^{1})
How many electrons must be removed from each of two 5.0kg copper spheres to make the electric force of repulsion between them equal in magnitude to the gravitational attraction between them?
There are three voltmeters of the same range but of resistance 10000 Ω, 8000 Ω and 4000 Ω respectively. The best voltmeter among these is the one whose resistance is
Final product formed on reduction of glycerol by hydriodic acid is
RCH = O + H₂ → RCH₂OH. For this reaction, catalyst is
Night blindness is caused by the deficiency of
For the equilibrium
K p = 9 a t m 2 at 37 º C . A 5 litre vessel contains 0.1 mole of LiCl.NH_{3}. How many moles of NH_{3} should be added to the flask at this temperature to derive the backward reaction for completion?
Use R = 0.082 atm L/mol K
If initial concentration is reduced to (1/4)th in a zero order reaction, the time taken for half the reaction to complete
Given that heat of neutralisation of strong acid and strong base is 57.1 kJ. Calculate the heat produced when 0.25 mole of HCl is neutralised with 0.25 mole of NaOH in aqueous solution.
The heat produced when 0.25 mole of HCl is neutralised with 0.25 mole of NaOH in aqueous solution is 57.1x1/4=14.275kJ
The decreasing order of the ionisation potential of the following elements is
As we move across a period from left to right, the nuclear charge increases and the atomic radius decreases though the principal quantum number of the valence shell remains the same. As a result, the valence electrons are more are more tightly held by the nucleus, hence ionisation potential keep on increasing. However, closed shell configuration (Ne), halffilled configuration (P) and completelyfilled configuration (Mg) are responsible for higher values of ionisation energy.
In the complex compound K₄[Ni(CN)₄], the oxidation no. of nickel is
Which of the following reagent can be used to convert benzene diazonium chloride into benzene ?
The element, which forms oxides in all oxidation states + 1 to + 5, is
The e.m.f. of a galvanic cell with electrode potentials of silver equal to + 0.80 V and that of copper equal to + 0.34 V is
Which of the following compound is the most soluble in water?
The best indicator for the detection of end point in titration of a strong base is
The pH of blood does not appreciably change by a small addition of acid or a base because blood
Which of the following does not give yellow ppt. with I₂/NaOH?
Product(s) of the following S N 1 reaction is/are :
Which of the following isomers will have the highest octane number ?
Which of the following metal oxides is antiferromagnetic in nature?
The radius of an atom of an element is 500 pm, if it crystallizes as a facecentred cubic lattice, then the edge length of the unit cell is
The normality of orthophosphoric acid having purity of 70% by weight and specific gravity 1.54 would be (H=1;O=16; P=31)
A solution contains nonvolatile solute of molecular mass M₂. which of the following can be used to calculate the molecules mass of solute in terms of osmotic pressure ?
Catalyst used in dimerisation of acetylene to prepare chloroprene is
The ionisation potential of hydrogen atom is 13.6 eV. The energy required to remove an electron in the n = 2 state of the hydrogen atom is __
The electronic configuration of the atom with atomic number 47 is ___
Element with atomic number 47 is silver (Ag) with configuration (actual is 1s^{2} 2^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{6} 4d^{10} 5s^{1}, i.e. its shows preference for completely filled orbital.
The change in entropy ∆S is positive for certain reaction and enthalpy change ∆H is also greater than zero at temperature T.The reaction is
The reaction of acidified, aqueous potassium iodide with aqueous hydrogen peroxide
is thought to involve the following steps
Which one of the following conclusions cannot be drawn from this information?
Which of the following sequence follows the IrwingWilliam order?
The correct order is according to decreasing charge to radius ratio.
Which of the following compounds to does not show Lassaigne's test for nitrogen?
If (a^{2})+16(b^{2})+49(c^{2})4ab28bc7ac=0, then a,b,c are in:
If 2^{ x} + 3 ^{y } = 17 and 2^{x + 2 } − 3^{ y + 1} = 5, then what is the value of x ?
AOB is the positive quadrant of the ellipse x ^{2 } ∕ a^{ 2 } + y 2 ∕ b^{ 2 } = 1, where OA = a, OB = b. The area between the arc AB and the chord AB of the ellipse is
The angle between the tangents drawn from (0,0) to the circle x^{2} + y^{2} + 4x  6y + 4 = 0 is
If 2x  3y = 0 is the equation of the common chord of the circles x^{2 }+ y^{2} + 4x = 0 and x^{2} + y^{2 }+ 2λy = 0, then the value of λ is
If the cube roots of unity are 1,ω,ω^{2} then the roots of the equation (x  1)^{3} + 8 = 0,are
The differential equation obtained by eliminating the arbitrary constants a and b from
Let f(x) = x, g(x) = 1/x and h(x) = f(x)g(x). Then h(x) = 1 if
Which is logically equivalent to "If today is Sunday, Matt cannot play hockey."?
Statements are logically equivalent to their contrapositives.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer
Assertion(A): Sum of the last 30 coefficients in the expansion of (1+x)^{59}, when expanded in ascending powers of x, is 2^{58}.
Reason(R): pth term from the end in the expansion of (x+y)^{n} is (n  p + 2)th term from the beginning.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer
Assertion(A): The number of terms in the expansion of which are integers is equal to 32.
Reason(R): In the binomial expansion of (x+y)^{n} , the (r+1)th term from the beginning is called general term (T_{r+1}) i.e, T_{r+1} = ^{n}C_{r} x^{n+r}y^{r}.
The line, among the following, that touches the parabola y^{2} = 4ax is
Each coefficients in the equation ax^{2}+bx+c=0 is determined by throwing an ordinary die. The probability that the equation will have equal roots is
If the two lines of regression of a bivariate distribution coincide, then the correlation coefficient ρ satisfies
The foot of perpendicular from (2,4) on the line x+y=1 is
The length of the subnormal to the curve y^{2} = 2px is
Set of equations a+b2c = 0, 2a3b+c = 0 and a5b+4c = α is consistent, if α equal to
If 1, ω, ω^{2} are cube roots of unity, the root of the equation (x1)^{3} + 8 = 0 are
The angle between the planes 2x  y + z = 6 and x + y + 2z = 7 is
The area of a parallelogram whose adjacent sides are a=i+2j+3k, b=3i2j+k, is
Suppose a,b,c are in A.P. and a^{2,}b^{2},c^{2} are in G.P. If a < b< c and a + b + c =3/2,then the value of a is
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer
Assertion(A): The number of ways of selecting two elements x and y from the set S = {1, 5, 9, 13,...,1093} such that x + y = 1094 is 137.
Reason(R) : The elements of S are in A.P. with common difference 4 and number of terms 274.
If A and B are matrices such that A+B and AB are defined, then
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