Four particles, each of mass M and equidistant from each other, move along a circle of radius R under the action of their mutual gravitational attraction. The speed of each particle is :?
A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it ? (1) A screw gauge having 100 divisions in the circular scale and pitch as 1 mm. (2) A screw gauge having 50 divisions in the circular scale and pitch as 1 mm. (3) A meter scale. (4) A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale & main scale has 10 divisions in 1 cm.
A parallel plate capacitor is made of two circular plates separated by a distance of 5 mm and with a dielectric of dielectric constant 2.2 between them. When the electric field in the dielectric is 3*10^4 V/m, the charge density of the positive plate will be close to :
The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is :
(For steel Young’s modulus is 2 × 10^11 N m−2 and coefficient of thermal expansion is 1.1 × 10^−5 K^−1)
Half life of 90Sr is 6.93 years. In a child body 1 
of 90Sr dopped in place of calcium, how many years will it take to reduce its concentration by 90% (Assume no involvement of Sr in metabolism).
Number of chiral centers in chloramphenicol is ?
Cl2 on reaction with hot & conc. NaOH gives two chlorine having products X and Y. On treatment with AgNO3, X gives precipitate. Determine average bond order of Cl and O bond in 'Y' ?
Each of solution A and B of 100 L containing 4 g NaOH and 9.8 g H2SO4. Find pH of solution which is obtain by mixing 40 L solution of A and 10 L solution of B.
Shown in the figure below is a meterbridge set up with null deflection in the galvanometer. The value of the unknown resistance R is
A 5 V battery with internal resistance 2 
and 2 V battery with internal resistance 1 are connected to a 10 resistor as shown in the figure. The current in the 10 resistor is
Consider a block of conducting material of resistivity 
shown in the figure. Current I enters at A and leaves from D. We apply the superposition principle to find voltage 
developed between B and C. The calculation is done in the following steps:
(i) Take current I entering from A and assume it to spread over a hemispherical surface in the block.
(ii) Calculate field E(r) at distance r from A by using Ohm’s law 
where j is the current per unit area at r.
(iii) From the r dependence of E(r), obtain the potential V(r) at r.
(iv) Repeat (i), (ii) and (iii) for current I leaving D and superpose results for A and D.
For current entering at A, the electric field at a distance r from A is
Consider a block of conducting material of resistivity shown in the figure. Current I enters at A and leaves from D. We apply the superposition principle to find voltage developed between B and C. The calculation is done in the following steps:
(i) Take current I entering from A and assume it to spread over a hemispherical surface in the block.
(ii) Calculate field E(r) at distance r from A by using Ohm’s law where j is the current per unit area at r.
(iii) From the r dependence of E(r), obtain the potential V(r) at r.
(iv) Repeat (i), (ii) and (iii) for current I leaving D and superpose results for A and D.
measured between B and C is
The resistance of a wire is 5 ohm at 50°C and 6 ohm at 100°C. The resistance of the wire at 0°C will be
A material B has twice the specific resistance of A. A circular wire made of B has twice the diameter of a wire made of A. Then for the two wires to have the same resistance, the ratio lB / lA of their respective lengths must be
The resistance of a bulb filament is 100 
at a temperature of 100º C. If its temperature coefficient of resistance be 0.005 per ºC, its resistance will become 200 at a temperature of
The current I drawn from the 5 volt source will be
In a Wheatstone’s bridge, three resistance P, Q and R connected in the three arms and the fourth arm is formed by two resistance S1 and S2 connected in parallel. The condition for bridge to be balanced will be
The Kirchhoff’s first law 
and second law (), 
where the symbols have their usual meanings, are respectively based on
In a potentiometer experiment, the balancing with a cell is at length 240 cm. On shunting, the cell with a resistance of 
, the balancing length becomes 120 cm. The internal resistance of the cell is
Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are R1 and R2 (R2 > R1). If the potential difference across the source having internal resistance R2 is zero, then
In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, What will be the value of the resistor R?
In a metre bridge experiment null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y?
An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4/3 and 2/3, then what will be the ratio of the currents passing through the wire?
13.4g of a sample of unstable hydrated salt: Na2SO4 . nH2O was found to contain 6.3g of water. Determine the number of water of crystallisation
X ml of H2 gas effuses through a hole in a container in 5 seconds. The time taken for the effusion of the same volume of the gas specified below under identical conditions is :
The behaviour of a real gas is usually depicted by plotting compressibility factor Z versus P at a constant temperature. At high temperature and high pressure, Z is usually more than one. This fact can be explained by van der Waals equation when
The temperature of an ideal gas is increased from 140 K to 560 K. If at 140 K the root mean square velocity of the gas molecule is V, at 560 K it becomes
Amongst LiCl, RbCl, BeCl2 and MgCl2 the compounds with greatest and least ionic character respectively are
In the formation of N2+ from N2 the electron is removed from
The pair having similar geometry is
The species which does not show paramagnetism is
The velocity of electron in the ground state hydrogen atom is 
. Its velocity in the second orbit would be
An electron is moving with a kinetic energy of 
. What will be de Broglie wave length for this electron?
SO2 is angular and CO2 is linear why?
Dipole moment of BF3 is zero.Why?
BaCO3 has got a higher decomposition temperature than MgCO3?
Calculate the ratio of K.E and P.E of an electron in a orbit?
What fraction of the volume of an atom of radius 10–8 cm is occupied by its nucleus if nuclear radius is 10^-12 cm?
The total current supplied to the circuit by the battery is
The total current supplied to the circuit by the battery is
The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter, what will be the change in the resistance of the wire?
A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The current I, in the circuit will be
The length of a wire of a potentiometer is 100 cm, and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is 
If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is
Find p and q such that px2 +5x+2=0 and 3x2 +10x+q=0. have both roots in common?
If equation 
has roots equal in magnitude & opposite in sign, then the value of k is?
Under the same conditions how many ml of 1M KOH and 0.5M H2SO4 solutions respectively when mixed for a total volume of 100 ml produce the highest rise in temperature
For the reaction 
are positive. The most favourable conditions for the reaction is
The ratio of closed packed atoms to tetrahedral holes in cubic close packing is
In a crystal some ions are missing from normal sites. This is an example of
The radius of Ag+ ion is 126 pm while that of I– ion is 216 pm. The coordination number of Ag+ in AgI is