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
The melting point of RbBr is 628°C, while that of NaF is 988°C. The principal reason that melting point of NaF is much higher than that of RbBr is that
The ionisation energy of solid NaCl is 180 kcal/mol. The dissolution of the solid in water is endothermic to the extent of 1 kcal per mol. If the solvation energies of Na+ and Cl– ions are in the ratio 6:5, what is the enthalpy of hydration of sodium ion
At 88°C benzene has a vapour pressure of 900 torr and toluene has a vapour pressure of 360 torr. What is the mole fraction of benzene in mixture with toluene that will boil at 88°C at 1 atm pressure assuming ideal solution.
When mercuric iodide is added to the aqueous solution of KI then the
Salts of A (atomic weight 7), B (atomic weight = 27) and C (atomic weight 48) were electrolysed under identical conditions using same quantity of electricity. It was found that when 2.1g of A was deposited, weights of B and C deposited were 2.7g and 7.2g. The valencies of A, B and C are respectively.
On moving a charge of 20 coulomb by 2 cm, 2 J of work is done, then what will be the potential difference between the points?
A charged ball B hangs from a silk thread S, which makes an 
with a large charged conducting sheet P, as shown in the figure. The surface charge density 
of the sheet is proportional to
Four charges equal to –Q are placed at the four corners of a square and a charge q is at its centre. What is the value of q If the system is in equilibrium?
A charged particle q is shot towards another charged particle Q which is fixed, with a speed v. It approaches Q upto a closest distance r and then returns. If q were given a speed 2v, what will b the closest distances of approach?
Two spherical conductors B and C having equal radii and carrying equal charges in them repel each other with a force F when kept apart at some distance. A third spherical conductor having the same radius as that of B but uncharged is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is
Three charges –q1, +q2 and –q3 are placed as shown in the figure. The x-component of the force on –q1 is proportional to
What is the work done in placing a charge of 8 × 10-18 coulomb on a condenser of capacity 100 micro-farad?
A thin spherical conducting shell of radius R has a charge q. Another charge Q is placed at the centre of the shell. The electrostatic potential at a point P at a distance R/2 from the centre of the shell is
A sheet of aluminum foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor
If Ihe electric flux entering and leaving an enclosed surface respectively is 
the electric charge inside the surface will be
What is capacitance (in F) of a spherical conductor with radius 1 meter?
If a charge q is placed at the centre of the line joining two equal charges Q such that the system is in equilibrium then what will be the value of q?
If there are n capacitors in parallel connected to V volt source, then the energy stored is equal to
If there are n capacitors in parallel connected to V volt source, then the energy stored is equal to