Recent questions tagged past papers

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

asked Dec 11, 2018 by pady_1

0 answers

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

asked Dec 11, 2018 by pady_1

0 answers

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

asked Dec 11, 2018 by pady_1

0 answers

Which one of the following statements about water is FALSE ?

asked Dec 11, 2018 by pady_1

0 answers

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

asked Dec 11, 2018 by pady_1

0 answers

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

asked Dec 11, 2018 by pady_1

0 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)

asked Dec 11, 2018 by pady_1

0 answers

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

0 answers

Galvanization is applying a coating of :

asked Dec 11, 2018 by pady_1

0 answers

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

0 answers

$18\; g$ 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

0 answers

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

0 answers

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

asked Dec 11, 2018 by pady_1

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

asked Dec 11, 2018 by pady_1

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

Choose the correct statement :

asked Dec 11, 2018 by pady_1

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

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

0 answers

$'nâ€™$ 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

0 answers

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

0 answers

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

0 answers

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

0 answers

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 contrapositive of the statement "If it is raining, then I will not come", is :

asked Dec 11, 2018 by pady_1

1 answer

If $f(x)=2 \tan^{-1}x+\sin^{-1} (\frac{2x}{1+x^2}),\; x>1$, then $f(5)$ is equal to:

asked Dec 11, 2018 by pady_1

1 answer

In a $\Delta ABC, \; \frac{a}{b} = 2 + \sqrt{3}$ and $\angle{C} = 60^{\circ}$. Then the ordered pair $(\angle{A}, \angle{B})$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

A factory is operating in two shifts, day and night, with 70 and 30 workers respectively. If per day mean wage of the day shift workers is Rs 54 and per day mean wage of all the workers is Rs 60, then per day mean wage of the night shift workers (in Rs) is :

asked Dec 11, 2018 by pady_1

1 answer

Ask Questions, Get Answers