Recent questions tagged 2006

The rate constant of a first order reaction at $27^{\circ}$ is $10^{-3} \min ^{-1})$. The temperature coefficient of this reaction is 2. What is the rate constant $ (in min^{-1})$ at $17^{\circ}C$ for this reaction ?

asked Oct 30, 2013 by meena.p

1 answer

Which of the following is not a characteristic property of chemical equilibrium?

asked Oct 30, 2013 by meena.p

1 answer

Which of the following set of variables give a straight line with a negative slope when plotted? (P= vapour pressure. T= Temperature in K)

asked Oct 30, 2013 by meena.p

1 answer

$AB$ is an ionic solid. The ionic radii of $A^{+}$ and $B^{-}$ are respectively $r_c$ and $r_a$. Lattice energy of AB is proportional to :

asked Oct 30, 2013 by meena.p

1 answer

Electronlysis of X gives Y at anode. Vacuum distillation of Y gives $H_2O_2$. The number of peroxy (O-O) bonds present in X and Y respectively are :

asked Oct 30, 2013 by meena.p

1 answer

The disperse phase, dispersion medium and nature of colloidal solution (lyophilic or lyophobic) of 'gold sol' respectively are :

asked Oct 30, 2013 by meena.p

1 answer

$CFCl_3$ is responsible for the decomposition of ozone to oxygen. Which of the following reacts with ozone to from oxygen?

asked Oct 30, 2013 by meena.p

1 answer

What is the time (in sec) required for depositing all the silver present in $125\;mL$ of $1\; M \;AgNO_3$ solution by passing a current of 241.25 A ? (IF=96500 coulombs)

asked Oct 30, 2013 by meena.p

1 answer

The energy of a photon is $3 \times 10^{-12}$ ergs. What is its wavelength in nm? $(h= 6.62 \times 10^{-27} ergs, c=3 \times 10^{10}cm/s)$

asked Oct 30, 2013 by meena.p

1 answer

The uncertainties in the velocities of two particle A and B are $0.05$ and $0.02\;m/s^{-1}$ respectively. The mass of B is five times to that of mass A. What is the ratio of uncertainties $\bigg(\large\frac{\Delta x_A}{\Delta x_B}\bigg)$ in their positions ?

asked Oct 30, 2013 by meena.p

1 answer

Which of the following statements is not correct ?

asked Oct 30, 2013 by meena.p

1 answer

Which of the following regents when heated with ethyl chloride, forms ethylene?

asked Oct 29, 2013 by meena.p

1 answer

Observe the following statements:

asked Oct 29, 2013 by meena.p

1 answer

Which of the following reactions an produce aniline as main product?

asked Oct 29, 2013 by meena.p

1 answer

Which of the following is not correct?

asked Oct 29, 2013 by meena.p

1 answer

Which of the following is used for making optical instruments?

asked Oct 29, 2013 by meena.p

1 answer

A molecule (X) has (i) four sigma bonds formed by the overlap of $sp^2$ and orbitals (ii) one sigma bond formed by $sp^2$ and $sp^2$ orbitals and (iii) one $\pi$ bond formed by $P_x$ and $P_z$ orbitals. Which of the following is X?

asked Oct 29, 2013 by meena.p

1 answer

what is the correct order of spin only magnetic moment (in BM) of $Mn^{2+},Cr^{2+}$ and $ V^{2+}?$

asked Oct 29, 2013 by meena.p

1 answer

The standard reduction potentials of $Zn^{2-} |Zn,Cu^{2+}|Cu$ and $Ag^{+} | Cu\;and\;Ag^{+}|Ag$ are respectively $-0.76,0.34$ and $0.8\;V$. The following cells were constructed :

asked Oct 29, 2013 by meena.p

1 answer

Consider a p-n junction as a capacitor, formed with p and n-materials acting as thin metal electron and depletion layer width acting as separation between them. Basing on this , assume that n-p-n transistor is working as an amplifier in CE configuration . If $C_1$ and $C_2$ are the base - emitter and collector- emitter junction capacitances, then:

asked Oct 29, 2013 by meena.p

1 answer

A free neutron decays spontaneously into:

asked Oct 29, 2013 by meena.p

1 answer

A proton, a deuteron (nucleus of $_1 H^2$) and an $\alpha$- particle with same kinetic energy enter a region of uniform magnetic field moving at right angles to the field. The ratio of the radii of their circular paths is :

asked Oct 29, 2013 by meena.p

1 answer

A oil drop having a mass $4.8 \times 10^{10}\;g$ and charge $2.4 \times 10^{-18}\;C$ stands still between two charged horizontal plates separated by a distance of 1 cm. If now the polarity of the plates is changed, instantaneous acceleration of the drop is : $(g= 10 ms^{-2}$)

asked Oct 29, 2013 by meena.p

1 answer

A small square loop of wire of side i is placed inside a large square loop of slide $L( L >>1)$. If the loops are coplanar and there centers coinside. the mutual induction of the system is directly proportional to :

asked Oct 29, 2013 by meena.p

1 answer

A rectangular loop of length l and breadth b is placed at distance of x from infinitely long wire carrying current i such that the direction of current is parallel to breadth. If the loop moves away from the current wire in a direction perpendicular to it with a velocity v, the magnitude of the emf in the loop is : ($\mu_o$= permeability of free space)

asked Oct 29, 2013 by meena.p

1 answer

When positively charged particle enters a uniform magnetic field with uniform velocity, its trajectory can be :

asked Oct 29, 2013 by meena.p

1 answer

If the cold junction is held at $0^{\circ}$, the same thermo emf V of a thermocouple varies as $V= 10 \times 10^{-6} t -\large\frac{1}{40} \times 10^{-6}t^2$, Where t is the temperature of the hot junction in $^{\circ}C$. The neutral temperature and the maximum value of thermo emf are respectively:

asked Oct 29, 2013 by meena.p

1 answer

Twelve cells, each having emf E volts are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12 cell battery is connected in series with an ammeter , an external resistance R ohms and a two- cell battery (two cells of the same type used earlier , connected perfectly in series). The current in the circuit when the 12 - cell battery and 2-cell battery aid each other is 3A and is 2A when they oppose each other . Then, the number of cells in 12 -cell battery that are connected wrongly is :

asked Oct 29, 2013 by meena.p

2 answers

One end of each of a resistance r capacitor C and resistance 2r are connected together. The other ends are respectively connected to the positive terminals of batteries, P, Q, R having respectively emf's E,E and 2E. The negative terminals of the batteries are then connected together. In this circuit, with steady current the potential drop across the capacitor is :

asked Oct 29, 2013 by meena.p

1 answer

Along the X-axis, three charges $\large\frac{q}{2},-q$ and $\large\frac{q}{2}$ are placed at $x=0,x= a$ and $x=2a$ respectively. The resultant electric potential at $x=a+r$ if ( a << r) is : $( \varepsilon_0$ is the permittivity of free space)

asked Oct 29, 2013 by meena.p

1 answer

The bob of simple pendulum is hanging vertically down from a fixed identical bob by means of a string of length l. If both bobs are charged with a charge q each , time period of the pendulum is : (ignore the radii of the bobs)

asked Oct 29, 2013 by meena.p

1 answer

Two short managers AB and CD are in the X-Y plane and are parallel to X-axis and coordinate of their centers respectively are (0,2) and (2,0). Line joining the north- south poles of CD is opposite to that of AB and lies along the positive X-axis. The resultant field induction due to AB and CD at a point P(2,2) is $100 \times 10^{-7}\;T$. When the poles of the magnet CD are reversed, the resultant field induction is $50 \times 10^{-7}T$. The value of magnetic moments of AB and CD (in $AM^2$) are :

asked Oct 29, 2013 by meena.p

1 answer

The effect due to uniform magnetic field on a freely suspended magnetic needle is as follows :

asked Oct 29, 2013 by meena.p

1 answer

In Young's double slit experiment, first slit has width four of the second slit. the ratio of the maximum intensity to the minimum intensity in the interference fringe system is :

asked Oct 29, 2013 by meena.p

1 answer

Match the appropriate pairs from List I and List II

asked Oct 29, 2013 by meena.p

1 answer

Dispersive power depends on the following :

asked Oct 29, 2013 by meena.p

1 answer

The two surfaces of a biconvex lens has same radii of curvatures. This lens is made of glass of refractive index 1.5 has a focal length 10 cm in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that the convex lenses. The two pieces are glued such that the convex surface touch each other. If this combination lens is immersed in water(refractive index=4/3), its focal length (in cm) is :

asked Oct 29, 2013 by meena.p

1 answer

An observer is standing 500 m away from a vertical hill, a police van sounding a siren of frequency 1000 Hz moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is 970 Hz. the frequency of the sound heard after reflection from the hill (in Hz) is about, (velocity of sound =$330\;ms^{-1}$):

asked Oct 29, 2013 by meena.p

1 answer

Two string A and b of lengths, $L_a=80\;cm$ and $L_B=x\;cm$ respectively are used separately in a sonometer. The ratio of their densities $(d_A/d_B)$ is $0.81$ The diameter of B is one -half that of A. If the string have the same tension and fundamental frequency the value of x is :

asked Oct 29, 2013 by meena.p

1 answer

Two solid spheres A and B made of the same material have radii $r_A$ and $r_B$ respectively. Both the sphere are cooled from the same temperature under the conditions valid for Newton's law of cooling. The ratio of the rate of change of temperature of A and B is :

asked Oct 29, 2013 by meena.p

1 answer

The cyclic process ABCD is shown below in the given P.V diagram. In the following answers the one that represents the same process as in the P-V diagram

asked Oct 29, 2013 by meena.p

1 answer

A given mass of a gas is compressed isothermally until its pressure is doubled. It is then allowed to expand adiabatically until its original volume is restored and its pressure is then found to be 0.75 of its initial pressure. The ratio of the specific heats of the gas is approximately :

asked Oct 29, 2013 by meena.p

1 answer

The temperature of a thin uniform circular disc, of one meter diameter is increased by $10^{\circ}C$. The percentage increase in moment of inertia of the disc about an axis passing through its center and perpendicular to the circular face: (linear coefficient of expansion $=11 \times 10^{-6}/^{\circ}C)$

asked Oct 29, 2013 by meena.p

1 answer

Two block of masses 1 kg and 2 kg are connected by a metal wire going over a smooth in figure. The breaking stress of the metal is $2 \times 10^{9} \;N/m^2$. What should be the minimum radius of the wire used if it is not to break? Take $g=10\;ms^2$

asked Oct 29, 2013 by meena.p

1 answer

An air bubble of radius 1 cm rises from the bottom portion through a liquid of density $1.5 g/cc$ at a constant speed of $0.250 \;cm^{-1}$.If the density of air is neglected, the coefficient of viscosity of the liquid is approximately, (In pas):

asked Oct 29, 2013 by meena.p

1 answer

Two soap bubbles combine to form a single bubble. In this process, the change in volume and surface area are respectively V and A. If P is the atmospheric pressure, and T is the surface tension of the soap solution, the following relation is true.

asked Oct 29, 2013 by meena.p

1 answer

Assertion (a) : Ductile metals are used to prepare thin wires. Reason (R) : In the stress - strain curve of ductile metals, the length between the points representing elastic limit and breaking point is very small.

asked Oct 29, 2013 by meena.p

1 answer

To the free end of spring hanging from a rigid support, a block of mass m is hung and slowly allowed to come to its equilibrium position. Then stretching in the spring is d. If the same block is attached to the same spring and allowed to fall suddenly, the amount of stretching is : (force constant , k)

asked Oct 28, 2013 by meena.p

1 answer

Assertion (a) : A particle of mass m dropped into a hole made along the diameter of the earth from one end to another and possess simple harmonic mention. Reason (R) : Gravitational force between any two particles is inversely proportional to the square of the distance between them.

asked Oct 28, 2013 by meena.p

1 answer

Assume the earths orbit around the sun as circular and the distance between their centers as D. Mass of the earth is M and its radius is R. If earth has an angular velocity $\omega _0$ with respect to its center and $\omega$with respect to the center of the sun, the total kinetic energy of earth is :

asked Oct 28, 2013 by meena.p

1 answer

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