The capacity of a pure capacitor is 1 farad. In D.C. circuits, its effective resistance will be
What percentage of original radioactive atoms is left after five half lives ?
A car is initially at rest on a circular track that has a radius of 40 m. The car then starts to move counter clockwise around the track, accelerating at constant angular acceleration of 1.0 rad/s2. The time it takes for the car to move half of the way around the track is
Two cells of the same emf are in series with an external resistance R. The internal resistance r1 is greater than r2. The p.d across the first cell is found to be zero. Then the value of R is
Current in the circuit
I = 2E / (R+r1+r2)
∴ Potential difference across first cell
= E − 2Er1 / (R+r1+r2)
On solving we get,
R = (r1−r2)
A mass m falls freely from rest. The linear momentum after it has fallen through a height h is
Cathode rays are similar to visible light rays in that
A wire of diameter 1 mm breaks under a tension of 1000 N. Another wire, of same material as that of the first one, but of diameter 2 mm breaks under a tension of
A transformer is used to reduce the mains supply of 220 V to 11 V. If the currents in primary and secondary coils are 5 A and 90 A respectively, efficiency of transformer is
A charge q is located at the centre of a cube. The electric flux through any face is
If a transistor amplifier has a gain of 20 dB, then the ratio of output to input power is
The acceleration on the surface of earth varies
A cube of weight 10N rests on a rough inclined plane of slope 3 in 5. The coefficient of friction is 0.6. The minimum force necessary to start the cube moving up the plane is
If a liquid is heated in weightlessness, the heat is transmitted through
For Boyle's law to hold the gas should be
If a force of 250 N act on body, the momentum acquired is 125 kg m/s, what is the period for which force acts on the body.
A current carrying circular loop is freely suspended by a long thread. The plane of the loop will point in the direction
A ferromagnetic material is heated above its Curie temperature. Which one is a correct statement ?
In a container, the velocity of water flowing through a hole at a depth h from the surface of water is 5 m-s⁻1. If the container has the hole at a depth 4h from the surface of water, then velocity of water flowing through the hole is
A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t sec is proportional
The length of second's hand in a watch is 1 cm. The change in velocity of its tip in 15 seconds is
Two bodies of mass 3 kg and 4 kg are suspended at the ends of massless string passing over a frictionless pulley. The acceleration of the system is (g=9.8 m/s2)
The period of simple pendulum is doubled, when
A body is projected at such an angle that the horizontal range is three times the greatest height. The angle of projection is
10 cm long wire is placed horizontally on the surface of water and is gently pulled up with a forceof 2 x 10⁻2N to keep the wire in equilibrium. The surface tension of water in N/m is
A consatnt torque of 31.4 N-m is exerted on a pivoted wheel. If angular acceleration of wheel is 4π rad/s2, then the moment of inertia of the wheel is
A ray of light strikes a glass plate at an angle θ. If angle between the reflected and refracted rays is a right angle, then refractive index of the glass plate is given by
The length of the second's hand in a watch is 1 cm. The magnitude of the change in the velocity of its tip in 15 s is
In 15s the hand moves through 90º.
If the speed of the tip is v, then
An electric lamp is marked 60 W, 230 V. The cost of a 1 Kwh of energy is Rs. 1.25. The cost of using this lamp 8 hrs a day for 30 days is
Radius of a soap bubble is\'r\', surface tension of soap solution is T. Then without increasing the temperature, how much energy will be needed to double its radius?
When a copper sphere is heated, maximum percentage change will be observed in
The phase difference between any two points on a wavefront is
If the amount of heat given to a system be 35 joules and the amount of work done by the system be -15 joules, then the change in the internal energy of the system is
Water has maximum density at
The frequency of a radar is 780 MHz. The frequency of the reflected wave from aeroplane is increased by 2.6 kHz. The velocity of the aeroplane is
From a waterfall, water is falling down at the rate of 100 kg/s on the blades of turbine. If the height of the ball is 100 m, then the power delivered to the turbine is approximately equal to
Number of metamers represented by molecular formula C₄H₁₀O is
Which of the following radicals will not be precipitated by passing H₂S in concentrated acid solution?
In the following reaction X and Y are are respectively,
Catalyst used in Rosenmund reduction is
Which of the following reacts with benzene in presence of anhydrous aluminium chloride and forms acetophenone?
For the energy levels in an atom, which one of the following statements is correct?
Among the following pairs, the one which illustrates the law of multiple proportions is
Proteins give blue colour with
Biuret Reaction - When the proteins are heated in presence of very dilute copper sulphate in alkaline medium,purple- voilet colour is obtained.
Ninhydrin Reaction - Ninhydrin is powerful oxidizing agent and causes oxidative decarboxylation of alpha amino acid producing an aldehyde with one carbon less than the parent amino acid. The reduced ninhydin hydrindatin then react with amion acids which has been liberated and the molecule of ninhydrin forms a blue colored compound.
The benedicts test is for sugar.
So correct answer is ninhydrin reagent.
Dimerisation in carboxylic acid is due to
The greater the s- character in an orbital the ... is its energy
The greater the s- character in an orbital, the shorter is the bond and greater is its strength. Thus, bond formed by sp hybridisation , as in acetylene is stronger as compare to ethane and ethene , because it has maximum bond energy.
Which one of the following statements is true?
A characteristic feature of reversible reactions is that they
The rate of reaction Cl₃C.CHO + NO → CHCl₃ + NO + CO is given by equation, Rate = K[Cl₃.CCHO][NO]. If concentration is expressed in moles/litre, the units of K are
If bond enthalpies of H-H,Br-Br and H-Br bonds are 433 ,192 and 364 KJ mol⁻1 respectively ,The ∆Hºfor the reaction H₂(g) + Br₂(g) →2HBr(g) is
The amount of heat required to raise the temperature of one mole of the substance through 1 K is called, its
Which of the following statement about an ideal dye is correct?
The IUPAC name of the compound
The standard reduction potentials of Ag, Cu, Co and Zn are 0.799, 0.337, -0.277 and -0.762 V respectively. Which of the following cells will have maximum cell EMF?
Which of the following elements has the lowest ionisation potential
The ionisation potential increases from O to F to Ne, because of increasing nuclear charge. The ionisation potential is highest for Ne because of its stable (ns2 np6) electronic configuration. But the ionisation potential of O is lower than N although the nuclear charge of O is higher. This is due to the extra-stability of exactly half-filled 2p-orbitals of N.
Among the following compounds (I-III), the correct order in reaction with electrophile is
1-Chloropropane and 2-chloropropane are
Which of the following solution cannot act as a buffer ?
When the product of pressure and volume is plotted against pressure for a given amount of the gas, the line obtained is
Positron annihilated, during its collision with electron, produces
The main product in the above reaction is
Which one of the following undergo reaction with 50% NaOH solution to give the corresponding alcohol and acid?
Which is true statement?
If on adding FeCl₃ solution to acidified Lassaigne solution, a blood red colouration is produced, it indicates the presence of
On the basis of mode of formation, polymers can be classified
In which of the following complexes, oxidation state of metal is zero ?
An aqueous solution containing 1 g of urea boils at 100.25ºC. The aqueous solution containing 3 g of glucose in the same volume will boil at (Molecular weight of urea and glucose are 60 and 180 respectively)
Elevation in boiling point when urea is dissolved in water:
As wt. of water is constant, hence can be neglected.
Zn converts its melting state to its solid state, it has HCP structure, then find out the nearest number of atoms
The migration of colloidal solute particles in a colloidal solution, when an electric current is applied to the solution is known as
In an oxidation - reduction reaction, dichromate ion is reduced to Cr +3 ion. The equivalent weight of K2Cr2O7 in this reaction is
A flask containing air (open to the atmosphere) is heated from 300K to 500 K. The percentage of air escaped to the atmosphere is
The maximum value of logx/x in (2, ∞) is
The volume of the solid obtained by revolving about y-axis the area enclosed between the ellipse x2 + 9y2 = 9 and the straight line x + 3y = 3, in the first quadrant is
If the coefficients of (2r + 1)th term and (r + 2)th term in the expansion of (1 + x)43 are equal, then the value of r is
The locus of the point of intersection of two perpendicular tangents to a circle is called
The locus of the mid-point of the intercept of the line x cos α + y sin α = p where p is a constant, intercepted between the co-ordinate axis is
If ω is a complex cube root of unity, the (1 + ω - ω2)(1 - ω + ω2) =
The length of latus rectum of the ellipse 3x2+4y2=12 is
If f: R → R is defined by f (x) = x − [ x ] , where [x] is the greatest integer not exceeding x, then the set of discontinuities of f is
If a, b, c are different and then x =
The integrating factor of a homogeneous eaqution a(x,y)dy+b(x,y) dx=0, is :
If y = sin x0 and z = log 10x then what is equal to ?
The first quartile is also known as:
If then A−1 =
If x and y are strictly positive such that x + y = 1, then the minimum value of x log x + y log y is
The A,B,C are three square matrix AB=AC⇒B=C, A is a
If sin⁻1 x = π/5, then cos⁻1 x equal
The standard deviation of 4, 5, 6, 7, .....13 is x, then the standard deviation of 14, 15, 16....23 is
The equation of a pair of lines passing through origin which make angle α with y = x is
If to form a ΔABC it is given that a=5, b=7, sinA= then possible triangles are
Thus is this case no triangle in possible
If ax2 + bx + c = a (x - α)(x - β), then a(αx + 1)(β x + 1) is equal to
P,Q,R and S have to deliver lecture, then in how many ways can the lectures be arranged?
Total no. of ways delivering lectures = 4P4 = 4! = 24
If P A = 0.4, P (A ∪ B) = 0.7 and A , B are independent then P(B) =
Let '*' be the binary operation defined on the set Z of all the integers as
a * b = a + b + 1 for all a, b ∈ Z. The identity element w.r.t. this operation is
If log 2,log (2x - 1),log (2x + 3) are in A.P.Then x is equal to
The angle between lines 3x+y-7=0 and x+2y+9=0 is
In a book of 500 pages, it is found that there are 250 typing errors. Assume that Poisson law holds for the number of errors per page. Then, the probability that a random sample of 2 pages will contain no error is
The derivative of
The tangent to the curve y=e2x at the point (0,1) meets the x-axis at
The period of |sin2x| is
The value of K for which (cos x + sin x)2+K sin x cos x -1=0 is an identity is
If vectors 2i+j+k and i-4j+λk are perpendicular, then λ=
then the angle between the vectorsis