Recent questions tagged 2016

Which one of the following complexes shows optical isomerism ?

asked Mar 14, 2017 by meena.p

1 answer

The pair having the same magnetic moment is :[At. No : $Cr= 24, Mn=25, Fe=26,Co=27$]

asked Mar 14, 2017 by meena.p

1 answer

Which of the following compounds is metallic and ferromagnetic ?

asked Mar 13, 2017 by meena.p

1 answer

The pair in which phosphorous atoms have a formal oxidation state of $+ 3$ is :

asked Mar 13, 2017 by meena.p

1 answer

The reaction of zinc with dilute and concentrated nitric acid, respectively produces :

asked Mar 13, 2017 by meena.p

1 answer

The main oxides formed on combustion of $Li, Na$ and $K$ in excess of air are, respectively :

asked Mar 13, 2017 by meena.p

1 answer

Which one of the following statements about water is FALSE ?

asked Mar 13, 2017 by meena.p

1 answer

Which one of the following ores is best concentrated by froth floatation method ?

asked Mar 13, 2017 by meena.p

1 answer

Which of the following atoms has the highest first ionization energy ?

asked Mar 13, 2017 by meena.p

1 answer

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 Mar 13, 2017 by meena.p

1 answer

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 Mar 13, 2017 by meena.p

1 answer

Galvanization is applying a coating of :

asked Mar 13, 2017 by meena.p

1 answer

The equilibrium constant at $298\;K$ for a reaction $A + B \rightleftharpoons C + D$ 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 Mar 13, 2017 by meena.p

1 answer

$18\; g$ 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 Mar 9, 2017 by meena.p

1 answer

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 Mar 9, 2017 by meena.p

1 answer

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

asked Mar 9, 2017 by meena.p

1 answer

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 $\large\frac{h}{\lambda}$ (where $\lambda$ is wavelength associated with electron wave) is given by

asked Mar 9, 2017 by meena.p

1 answer

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 Mar 9, 2017 by meena.p

1 answer

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 Mar 9, 2017 by meena.p

1 answer

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

asked Mar 8, 2017 by meena.p

1 answer

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

asked Mar 8, 2017 by meena.p

1 answer

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

asked Mar 8, 2017 by meena.p

1 answer

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 Mar 8, 2017 by meena.p

1 answer

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 Mar 8, 2017 by meena.p

1 answer

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 and brought in contact, the $45^{th}$ 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 Mar 8, 2017 by meena.p

1 answer

Choose the correct statement :

asked Mar 7, 2017 by meena.p

1 answer

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 Mar 7, 2017 by meena.p

1 answer

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 Mar 7, 2017 by meena.p

1 answer

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

asked Mar 7, 2017 by meena.p

1 answer

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 Mar 7, 2017 by meena.p

1 answer

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 Mar 6, 2017 by meena.p

1 answer

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

asked Mar 6, 2017 by meena.p

1 answer

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

asked Mar 6, 2017 by meena.p

1 answer

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 Mar 6, 2017 by meena.p

1 answer

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 $\large\frac{B_A}{B_B}$ is :

asked Mar 6, 2017 by meena.p

1 answer

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

asked Mar 6, 2017 by meena.p

1 answer

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 Mar 6, 2017 by meena.p

1 answer

The region between two concentric spheres of radii $‘a’$ and $‘b’$, respectively (see figure), has volume charge density $\rho = \large\frac{A}{r}$, 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 Mar 6, 2017 by meena.p

1 answer

A uniform string of length $20\;m$ is suspended from a rigid support. A short wave pulse in 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 Mar 6, 2017 by meena.p

1 answer

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

asked Mar 2, 2017 by meena.p

1 answer

‘n’ 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 Mar 2, 2017 by meena.p

1 answer

An ideal gas undergoes a quasi static, reversible process in which its molar heat capacity Cremains 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 Mar 2, 2017 by meena.p

1 answer

A pendulum clock loses $12\;s$ a day if the temperature is $40 ^{\circ} C $ and gains $4s\;a$ day if the temperature is $20 ^{\circ}C$. 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 Mar 2, 2017 by meena.p

1 answer

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 Mar 2, 2017 by meena.p

1 answer

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 Mar 2, 2017 by meena.p

1 answer

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 Mar 1, 2017 by meena.p

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 Mar 1, 2017 by meena.p

1 answer

A particle of mass m is moving along the side of a square of side $‘a’$, 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 Mar 1, 2017 by meena.p

1 answer

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 Mar 1, 2017 by meena.p

1 answer

(i) Find the magnitude and direction of current in $1 \Omega$ resistor in the given circuit . (ii) Two students X and Y perform an experiment on potentio meter separately using the circuit diagram shown below. Keeping other things unchanged (a) X increases the value of resistance R, (b) Y decrease the value of resistance S in the set up. How will these change affect the position of null point in each case and why ? (a) Use Kirchhoff's rules , calculate the current in the arm AC of the given circuit ? (b) On what principle does the meter bridge work ? Why are the metal strips used in the bridge ?

asked Jun 10, 2016 by meena.p

1 answer

Ask Questions, Get Answers