Recent questions tagged 23

If the rate constant for a first order reaction is k,the time (t) required for the completion of 90% of the reaction is given by :-

asked Jul 8, 2019 by pady_1

1 answer

The First Law of thermodynamics states that :

asked Dec 19, 2018 by pady_1

0 answers

In a compensated pendulum two rods of different metals are used with their lengths in ratio of $2:3$. The coefficients of linear expansions for metals in the ratio is :

asked Dec 19, 2018 by pady_1

1 answer

The displacement $r$ of a charge $Q$ in an electric field $\overrightarrow{E} = c_1 \hat{i} + c_2 \hat{j} + c_3 \hat{k}$ is $\overrightarrow{r} = a \hat{i} + b \hat{j}$. The work done is :

asked Dec 19, 2018 by pady_1

0 answers

A wire in the form of a square of side $'a'$ carries a current $'i'$. Then the magnetic induction at the centre of the square is : (Magnetic permeability of free space = $\mu_0$)

asked Dec 11, 2018 by pady_1

0 answers

Heat given to a body which raises its temperature by $1^{\circ}C$ is :

asked Dec 11, 2018 by pady_1

0 answers

An ammeter reads upto $1A$. Its internal resistance is $0.81 \Omega$. To increase the range to $10 \;A$, the value of the required shunt is:

asked Dec 11, 2018 by pady_1

0 answers

In a collinear collision, a particle with an initial speepd $v_0$ strikes a stationary particle of the same mass. If the final kinetic energy $50\%$ greater than the original kinetic energy, the magnitude of the relative velocity between the two particles, after collision, is :

asked Dec 11, 2018 by pady_1

0 answers

It two different numbers are taken from the set $\{0,1,2,3,....., 10\}$; then the probability that their sum as well as absolute difference are both multiple of 4, is

asked Dec 11, 2018 by pady_1

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 Dec 11, 2018 by pady_1

0 answers

An electromagnetic wave travelling in the $x$-direction has frequency of $2 \times 10^{14}\; Hz$ and electric field amplitude of $27\; Vm^{-1}$ . From the options given below, which one describes the magnetic field for this wave ?

asked Dec 11, 2018 by pady_1

0 answers

A green light is incident from the water to the air – water interface at the critical angle ($\theta$). Select the correct statement

asked Dec 11, 2018 by pady_1

0 answers

For gaseous state, if most probable speed is denoted by $C^*$, average speed by $\overline{C}$ and mean square speed by C, then for a large number of molecules the ratios of these speeds are :

asked Dec 11, 2018 by pady_1

0 answers

Let P and Q be $3 \times 3$ matrices with $P \neq Q$. If $P^3 = Q^3$ and $P^2Q= Q^2P$, then determinant of $(P^2+Q^2)$ is equal to

asked Dec 11, 2018 by pady_1

0 answers

Direction : The question has a paragraph followed by two statements, Statement-1 and Statement-2. Of the given four alternatives after the statements, choose the one that describes the statements. A thin air film is formed by putting the convex surface of a plane - convex lens over a plane glass plate. With monochromatic light, this film gives an interference pattern due to light reflected from the top (convex) surface and the bottom (glass plate) surface of the film. Statement-1: When light reflects from the air-glass plate interface, the reflected wave suffers a phase change of $\pi$. Statement-2:The centre of the interference pattern is dark.

asked Dec 11, 2018 by pady_1

0 answers

The Gibbs energy for the decomposition of $Al_2O_3$ at $500^{\circ}C$ is as follows : $\large\frac{2}{3}$$Al_2O_3 \to \large\frac{4}{3}$$Al+O_2, \Delta_rG=+966\;kJ\;mol^{-1}$ The potential difference needed for electrolytic reduction of $Al_2O_3$ at $500^{\circ}C$ is at least

asked Dec 11, 2018 by pady_1

0 answers

Three sound waves of equal amplitudes has frequencies $(v-1), v, (v+1)$. They superpose to give beats. The number of beats produced per second will be

asked Nov 29, 2018 by pady_1

0 answers

23. The first two terms of a geometric progression add up to 12. The sum of the third and the fourth terms is 48. If the terms of the geometric progression are alternately positive and negative, then the first term is

asked Nov 29, 2018 by pady_1

0 answers

Let $ A = \begin{bmatrix} 5 & 5 \alpha & \alpha \\\ 0 & \alpha & 5 \alpha \\ 0 & 0 & 5 \end{bmatrix}$ If $|A^2| = 25$, then $|\alpha|$ equals :

asked Nov 29, 2018 by pady_1

0 answers

The time taken by a photoelectron to come out after the photon strikes is approximately :

asked Nov 13, 2018 by pady_1

0 answers

If the roots of the equation $x^2 - bx + c = 0$ be two consecutive integers, then $b^2 - 4c$ equals :

asked Nov 5, 2018 by pady_1

0 answers

Which of the following is incorrect regarding the first law of thermodynamics ?

asked Nov 5, 2018 by pady_1

0 answers

The sides of the triangle are $\sin \alpha, \cos \alpha$ and $\sqrt{1 + \sin \alpha \cos \alpha}$ for some $0 < \alpha < \frac{\pi}{2}$. Then the greatest angle of the triangle is

asked Nov 5, 2018 by pady_1

0 answers

A pendulum is hung from the roof of a sufficiently high building and is moving freely to and fro like a simple harmonic oscillator. The acceleration of the bob of the pendulum is $20 \; m/s^2$ at a distance of 5 m from the mean position. The time period of oscillation is :

asked Aug 21, 2018 by pady_1

2 answers

The correct order of the stoichiometries of $AgCl$ formed when $AgNO_3$ in excess is treated with the complexes : $CoCl_3.6NH_3, CoCl_3.5NH_3, CoCl_3.4NH_3$ respectively is -

asked Aug 21, 2018 by pady_1

1 answer

In Which of the following options the order of arrangement does not agree with the variation of property indicate against it ?

asked Aug 21, 2018 by pady_1

1 answer

Hybridization involved in complex the $[Ni(CN)_4]^{2–}$ is : (At. No. Ni = 28)

asked Aug 21, 2018 by pady_1

1 answer

Two thin dielectric slabs of dielectric constants $K_1$ and $K_2 ( K_1 < K_2)$ are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field 'E' between the plates with distance 'd' as measured from plate P is correctly shown by:

asked Aug 20, 2018 by pady_1

1 answer

Two pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is r. Now the strings are rigidly clamped at half the height. The equilibrium separation between the balls now become -

asked Aug 20, 2018 by pady_1

1 answer

In an electrical circuit R, L, C and an a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the ciruit is $\frac{\pi}{3}$ . If instead, C is removed from the circuit, the phase difference is again $\frac{\pi}{3}$ . The power factor of the circuit is

asked Aug 20, 2018 by pady_1

1 answer

There are four light-weight -rood samples A, B, C, D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted : (a) A is feebly repelled (b) B is feebly attracted (c) C is strongly attracted (d) D remains unaffected Which one of the following is true ?

asked Aug 16, 2018 by pady_1

1 answer

The device that can act as a complete electronic circuit is –

asked Jul 26, 2018 by pady_1

1 answer

A wave in a string has an amplitude of 2 cm. The wave travels in the +ve direction of x-axis with speed of 128 m/s and it is noted that 5 complete waves fit in 4 m length of the string. The equation describing the wave is

asked Jul 26, 2018 by pady_1

1 answer

The electric potential at a point in free space due to a charge Q coulomb is $Q\times 10^{11}$ volts. The electric field at that point is -

asked Jul 26, 2018 by pady_1

1 answer

Charge +q and â€“q are placed at points A and B respectively which are at distance $2L$ apart, C is the midpoint between A and B. The work done in moving a charge + Q along the semicircle CRD is:-

asked Jul 26, 2018 by pady_1

1 answer

The core of a transformer is laminated because:-

asked Jul 25, 2018 by pady_1

1 answer

A coil in the shape of an equilateral triangle of side l is suspended between the pole pieces of a r permanent magnet such that B is in place of the coil. If due to a current i in the triangle a torque ? acts on it, the side l of the triangle is-

asked Jul 24, 2018 by pady_1

1 answer

The magnetic flux through a circuit of resistance R changes by an amount $\Delta \phi$ in a time $\Delta t$. Then the total quantity of electric charges Q that passes any point in the circuit during the time $\Delta t$ is represented by :-

asked Jul 24, 2018 by pady_1

2 answers

The potential energy of a simple harmonic oscillator when the particle is half way to its end point is -

asked Jul 24, 2018 by pady_1

1 answer

An object of mass 3kg is at rest. Now a force of F = 6t 2 i + 4t j is applied on the object then velocity of object at t = 3 second is : -

asked Jul 23, 2018 by pady_1

1 answer

A cyclindrical rod having temperature $T_1$ and $T_2$ at its end. The rate of flow of heat $Q_1$ cal/sec. If all the linear dimension are doubled keeping temperature remain const. then rate of flow of heat $Q_2$ will be :-

asked Jul 20, 2018 by pady_1

1 answer

For adjoining fig., The magnetic field at point, 'P' will be : 5A P 2.5A 2.5 m 5m

asked Jul 20, 2018 by pady_1

1 answer

Two coil have a mutual inductance 0.005 H. The current changes in first coil according to equation $I = I_{0}$ sin $\omega$t where $I_{0} = 2A$ and $\omega= 100\pi$ rad/sec. The maximum value of emf in second coil is :

asked Jun 15, 2018 by pady_1

1 answer

Pick the odd one out : HOSTEL, HOTEL, CLUB, MOTEL

asked Dec 31, 2015 by pady_1

1 answer

A survey was done in all schools of Lucknow, where each student was asked for their favorite subject. Result of survey is shown in the circle chart. , Which is the least liked subject among students in Lucknow ?

asked Dec 31, 2015 by pady_1

0 answers

The juice cart sells 163.59 liters of grape juice on Sunday and 19.11 liters more than this amount on Monday. The following day, 12.89 liters less grape juice than on Monday were sold. How many liters of grape juice were sold on the Tuesday?

asked Dec 31, 2015 by pady_1

0 answers

Write True or False. Multiplicative inverse of 19 is $\large\frac{1}{19}$.

asked Dec 31, 2015 by pady_1

0 answers

An examinee scored 585 marks out of 900 marks. What percentage of marks did he score?

asked Dec 31, 2015 by pady_1

1 answer

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