Recent questions tagged 2016

For a linear plot of $\log (x/m)$ versus $\log p$ in a Freundlich adsorption isotherm, which of the following statements is correct ? ($k$ and $n$ are constants)

asked Dec 11, 2018 by pady_1

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Decomposition of $H_2O_2$ follows a first order reaction. In fifty minutes the concentration of $H_2O_2$ decreases from $0.5$ to $0.125\; M$ in one such decomposition. When the concentration of $H_2O_2$ reaches $0.05\; M$, the rate of formation of $O_2$ will be :

asked Dec 11, 2018 by pady_1

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Galvanization is applying a coating of :

asked Dec 11, 2018 by pady_1

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The equilibrium constant at $298 \;K$ for a reaction $A+B⇌C+D$ is $100$. If the initial concentration of all the four species were $1\; M$ each, then equilibrium concentration of D (in $mol\; L^{−1}$ ) will be :

asked Dec 11, 2018 by pady_1

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$18\; g$ glucose $(C_6H_{12}O_6 )$ is added to $178.2\; g$ water. The vapor pressure of water (in torr) for this aqueous solution is :

asked Dec 11, 2018 by pady_1

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The heats of combustion of carbon and carbon monoxide are $−393.5$ and $−283.5\; kJ \;mol^{−1}$ , respectively. The heat of formation (in kJ) of carbon monoxide per mole is :

asked Dec 11, 2018 by pady_1

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The species in which the N atom is in a state of sp hybridization is :

asked Dec 11, 2018 by pady_1

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A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference $V$ esu. If $e$ and $m$ are charge and mass of an electron, respectively, then the value of $h/ \lambda$ (where $\lambda$ is wavelength associated with electron wave) is given by :

asked Dec 11, 2018 by pady_1

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Two closed bulbs of equal volume $(V)$ containing an ideal gas initially at pressure pi and temperature $T_1$ are connected through a narrow tube of negligible volume as shown in the figure below. The temperature of one of the bulbs is then raised to $T_2$ . The final pressure $p_f$ is :

asked Dec 11, 2018 by pady_1

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At $300\; K$ and $1 \;atm$, $15\; mL$ of a gaseous hydrocarbon requires $375\; mL$ air containing $20\%\; O_2$ by volume for complete combustion. After combustion the gases occupy $330\; mL$. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is :

asked Dec 11, 2018 by pady_1

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For a common emitter configuration, if $\alpha$ and $\beta$ have their usual meanings, the incorrect relationship between $\alpha$ and $\beta$ is

asked Dec 11, 2018 by pady_1

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Identify the semiconductor devices whose characteristics are given below, in the order (a), (b), (c), (d) :

asked Dec 11, 2018 by pady_1

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In an experiment for determination of refractive index of glass of a prism by $i− \delta$, plot, it was found that a ray incident at angle $35^{\circ}$, suffers a deviation of $40^{\circ}$ and that it emerges at angle $79^{\circ}$ ⋅ Ιn that case which of the following is closest to the maximum possible value of the refractive index ?

asked Dec 11, 2018 by pady_1

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A galvanometer having a coil resistance of $100 \Omega$ gives a full scale deflection, when a current of $1\; mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\; A$, is :

asked Dec 11, 2018 by pady_1

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A pipe open at both ends has a fundamental frequency f in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now :

asked Dec 11, 2018 by pady_1

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A screw gauge with a pitch of $0.5\; mm$ and a circular scale with $50$ divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the 45th division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is $0.5\; mm$ and the $25^{th}$ division coincides with the main scale line ?

asked Dec 11, 2018 by pady_1

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Choose the correct statement :

asked Dec 11, 2018 by pady_1

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If $a,\; b,\; c,\; d$ are inputs to a gate and $x$ is its output, then, as per the following time graph, the gate is :

asked Dec 11, 2018 by pady_1

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Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively. Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed numbers of A and B nuclei will be :

asked Dec 11, 2018 by pady_1

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Radiation of wavelength $\lambda$, is incident on a photocell. The fastest emitted electron has speed $v$. If the wavelength is changed to $\frac{3λ}{4}$ , the speed of the fastest emitted electron will be :

asked Dec 11, 2018 by pady_1

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The box of a pin hole camera, of length L, has a hole of radius $a$. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda$ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say $b_{min}$) when :

asked Dec 11, 2018 by pady_1

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An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer the tree appears :

asked Dec 11, 2018 by pady_1

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Arrange the following electromagnetic radiations per quantum in the order of increasing energy : A : Blue light B : Yellow light C : X-ray D : Radiowave.

asked Dec 11, 2018 by pady_1

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An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to :

asked Dec 11, 2018 by pady_1

0 answers

Hysteresis loops for two magnetic materials A and B are given below : These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use :

asked Dec 11, 2018 by pady_1

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Two identical wires A and B, each of length $‘l’$, carry the same current $I$. Wire A is bent into a circle of radius $R$ and wire $B$ is bent to form a square of side $‘a’$. If $B_A$ and $B_B$ are the values of magnetic field at the centres of the circle and square respectively, then the ratio $\frac{B_A}{B_B}$ is :

asked Dec 11, 2018 by pady_1

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The temperature dependence of resistances of Cu and undoped Si in the temperature range 300-400 K, is best described by :

asked Dec 11, 2018 by pady_1

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A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the $4\; \mu F$ and $9\; \mu F$ capacitors), at a point distant 30 m from it, would equal :

asked Dec 11, 2018 by pady_1

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The region between two concentric spheres of radii â€˜aâ€™ and â€˜bâ€™, respectively (see figure), has volume charge density $\rho = \frac{A}{r}$ , where A is a constant and r is the distance from the centre. At the centre of the spheres is a point charge Q. The value of A such that the electric field in the region between the spheres will be constant, is :

asked Dec 11, 2018 by pady_1

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A uniform string of length 20 m is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the support is : (take $g = 10\; ms^{−2}$ )

asked Dec 11, 2018 by pady_1

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A particle performs simple harmonic motion with amplitude A. Its speed is trebled at the instant that it is at a distance $\frac{2A}{3} $ from equilibrium position. The new amplitude of the motion is :

asked Dec 11, 2018 by pady_1

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$'nâ€™$ moles of an ideal gas undergoes a process $A \to B$ as shown in the figure. The maximum temperature of the gas during the process will be :

asked Dec 11, 2018 by pady_1

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An ideal gas undergoes a quasi static, reversible process in which its molar heat capacity C remains constant. If during this process the relation of pressure P and volume V is given by $PV^n$=constant, then $n$ is given by (Here $C_P$ and $C_V$ are molar specific heat at constant pressure and constant volume, respectively) :

asked Dec 11, 2018 by pady_1

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A pendulum clock loses 12 s a day if the temperature is $40^oC$ and gains 4 s a day if the temperature is $20^oC$. The temperature at which the clock will show correct time, and the co-efficient of linear expansion ($\alpha$) of the metal of the pendulum shaft are respectively :

asked Dec 11, 2018 by pady_1

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A satellite is revolving in a circular orbit at a height 'h' from the earth's surface (radius of earth R; $h << R$). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth's gravitational field, is close to : (Neglect the effect of atmosphere.)

asked Dec 11, 2018 by pady_1

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A roller is made by joining together two cones at their vertices O. It is kept on two rails AB and CD which are placed asymmetrically (see figure), with its axis perpendicular to CD and its centre O at the centre of line joining AB and CD (see figure). It is given a light push so that it starts rolling with its centre O moving parallel to CD in the direction shown. As it moves, the roller will tend to :

asked Dec 11, 2018 by pady_1

0 answers

A person trying to lose weight by burning fat lifts a mass of $10\; kg$ upto a height of $1\; m \;1000\; times$. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up ? Fat supplies $3.8 \times 10^7 \;J$ of energy per kg which is converted to mechanical energy with a $20\%$ efficiency rate. Take $g=9.8 \;ms^{−2}$ :

asked Dec 11, 2018 by pady_1

1 answer

A point particle of mass m, moves along the uniformly rough track PQR as shown in the figure. The coefficient of friction, between the particle and the rough track equals $\mu$. The particle is released, from rest, from the point P and it comes to rest at a point R. The energies, lost by the ball, over the parts, PQ and QR, of the track, are equal to each other, and no energy is lost when particle changes direction from PQ to QR. The values of the coefficient of friction $\mu$ and the distance $x(=QR)$, are, respectively close to :

asked Dec 11, 2018 by pady_1

0 answers

A particle of mass m is moving along the side of a square of side â€˜aâ€™, with a uniform speed $v$ in the x-y plane as shown in the figure : Which of the following statements is false for the angular momentum $\overrightarrow{L}$ about the origin ?

asked Dec 11, 2018 by pady_1

0 answers

A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90 s, 91 s, 95 s and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be :

asked Dec 11, 2018 by pady_1

0 answers

The angle of incidence for a ray of light at a refracting surface of a prism is $45^o$. The angle of prism is $60^o$. If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are :

asked Aug 21, 2018 by pady_1

1 answer

A particle of mass 10 g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to $8 \times 10^{–4} J$ by the end of the second revolution after the beginning of the motion ?

asked Aug 21, 2018 by pady_1

1 answer

A refrigerator works between $4^oC$ and $30^oC$. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is : (Take 1 cal = 4.2 Joules)

asked Aug 21, 2018 by pady_1

1 answer

When an $\alpha$-particle of mass 'm' moving with velocity 'v' bombards on a heavy nucleus of charge 'Ze', its distance of closest approach from the nucleus depends on m as :

asked Aug 21, 2018 by pady_1

1 answer

An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is :

asked Aug 21, 2018 by pady_1

1 answer

An inductor $20 \;mH$, a capacitor $50 \; \mu F$ and a resistor $40\; \Omega$ are connected in series across a source of emf $V = 10 \sin 340t$. The power loss in A.C. circuit is :

asked Aug 21, 2018 by pady_1

1 answer

A uniform rope of length $L$ and mass $m_1$ hangs vertically from a rigid support. A block of mass $m_2$ is attached to the free end of the rope. A transverse pulse of wavelength $\lambda_1$ is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is $\lambda_2$. The ratio $\lambda_2/\lambda_1$ is :

asked Aug 21, 2018 by pady_1

1 answer

A small signal voltage $V(t )= V_0 \sin \omega t$ is applied across an ideal capacitor C :

asked Aug 21, 2018 by pady_1

1 answer

What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop ?

asked Aug 21, 2018 by pady_1

1 answer

A uniform circular disc of radius 50 cm at rest is free to turn about an axis which is perpendicular to its plane and passes through its centre. It is subjected to a torque which produces a constant angular acceleration of $2.0\; rad\; s^{–2}$ . Its net acceleration in $ms^{–2}$ at the end of 2.0 s is approximately :

asked Aug 21, 2018 by pady_1

1 answer

Ask Questions, Get Answers

For a linear plot of $\log (x/m)$ versus $\log p$ in a Freundlich adsorption isotherm, which of the following statements is correct ? ($k$ and $n$ are constants)

Decomposition of $H_2O_2$ follows a first order reaction. In fifty minutes the concentration of $H_2O_2$ decreases from $0.5$ to $0.125\; M$ in one such decomposition. When the concentration of $H_2O_2$ reaches $0.05\; M$, the rate of formation of $O_2$ will be :

Galvanization is applying a coating of :

The equilibrium constant at $298 \;K$ for a reaction $A+B⇌C+D$ is $100$. If the initial concentration of all the four species were $1\; M$ each, then equilibrium concentration of D (in $mol\; L^{−1}$ ) will be :

$18\; g$ glucose $(C_6H_{12}O_6 )$ is added to $178.2\; g$ water. The vapor pressure of water (in torr) for this aqueous solution is :

The heats of combustion of carbon and carbon monoxide are $−393.5$ and $−283.5\; kJ \;mol^{−1}$ , respectively. The heat of formation (in kJ) of carbon monoxide per mole is :

The species in which the N atom is in a state of sp hybridization is :

A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference $V$ esu. If $e$ and $m$ are charge and mass of an electron, respectively, then the value of $h/ \lambda$ (where $\lambda$ is wavelength associated with electron wave) is given by :

Two closed bulbs of equal volume $(V)$ containing an ideal gas initially at pressure pi and temperature $T_1$ are connected through a narrow tube of negligible volume as shown in the figure below. The temperature of one of the bulbs is then raised to $T_2$ . The final pressure $p_f$ is : <br>

For a common emitter configuration, if $\alpha$ and $\beta$ have their usual meanings, the incorrect relationship between $\alpha$ and $\beta$ is

Identify the semiconductor devices whose characteristics are given below, in the order (a), (b), (c), (d) : <br>

A galvanometer having a coil resistance of $100 \Omega$ gives a full scale deflection, when a current of $1\; mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\; A$, is :

A pipe open at both ends has a fundamental frequency f in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now :

Choose the correct statement :

If $a,\; b,\; c,\; d$ are inputs to a gate and $x$ is its output, then, as per the following time graph, the gate is : <br>

Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively. Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed numbers of A and B nuclei will be :

Radiation of wavelength $\lambda$, is incident on a photocell. The fastest emitted electron has speed $v$. If the wavelength is changed to $\frac{3λ}{4}$ , the speed of the fastest emitted electron will be :

An observer looks at a distant tree of height 10 m with a telescope of magnifying power of 20. To the observer the tree appears :

Arrange the following electromagnetic radiations per quantum in the order of increasing energy : <br> A : Blue light <br> B : Yellow light <br> C : X-ray <br> D : Radiowave.

An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to :

Hysteresis loops for two magnetic materials A and B are given below : <br> <br> These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use :

The temperature dependence of resistances of Cu and undoped Si in the temperature range 300-400 K, is best described by :

A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the $4\; \mu F$ and $9\; \mu F$ capacitors), at a point distant 30 m from it, would equal : <br>

A uniform string of length 20 m is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the support is : (take $g = 10\; ms^{−2}$ )

A particle performs simple harmonic motion with amplitude A. Its speed is trebled at the instant that it is at a distance $\frac{2A}{3} $ from equilibrium position. The new amplitude of the motion is :

$'nâ€™$ moles of an ideal gas undergoes a process $A \to B$ as shown in the figure. The maximum temperature of the gas during the process will be : <br>

A pendulum clock loses 12 s a day if the temperature is $40^oC$ and gains 4 s a day if the temperature is $20^oC$. The temperature at which the clock will show correct time, and the co-efficient of linear expansion ($\alpha$) of the metal of the pendulum shaft are respectively :

A satellite is revolving in a circular orbit at a height 'h' from the earth's surface (radius of earth R; $h << R$). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth's gravitational field, is close to : (Neglect the effect of atmosphere.)

A particle of mass m is moving along the side of a square of side â€˜aâ€™, with a uniform speed $v$ in the x-y plane as shown in the figure : <br> <br> Which of the following statements is false for the angular momentum $\overrightarrow{L}$ about the origin ?

A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90 s, 91 s, 95 s and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be :

The angle of incidence for a ray of light at a refracting surface of a prism is $45^o$. The angle of prism is $60^o$. If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are :

A particle of mass 10 g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to $8 \times 10^{–4} J$ by the end of the second revolution after the beginning of the motion ?

A refrigerator works between $4^oC$ and $30^oC$. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is : (Take 1 cal = 4.2 Joules)

When an $\alpha$-particle of mass 'm' moving with velocity 'v' bombards on a heavy nucleus of charge 'Ze', its distance of closest approach from the nucleus depends on m as :

An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is :

An inductor $20 \;mH$, a capacitor $50 \; \mu F$ and a resistor $40\; \Omega$ are connected in series across a source of emf $V = 10 \sin 340t$. The power loss in A.C. circuit is :

A small signal voltage $V(t )= V_0 \sin \omega t$ is applied across an ideal capacitor C :

What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop ?