Recent questions tagged 30

An alkene "A" on reaction with $O_3$ and $Zn-H_2O$ gives propanone and ethanal in equimolar ratio.Addition of HCl to alkene "A" gives "B" as the major product. The structure of product "B" is :-

asked Jul 8, 2019 by pady_1

1 answer

A compound microscope has an objective of focal length 4 mm and an eye piece of focal length 25 mm. The objective produces a real image at a distance of 180 mm. If the eye piece is in normal adjustment the magnification is :

asked Dec 19, 2018 by pady_1

1 answer

A glass tube $1.5\;m$ long and open at both ends is immersed vertically in a mind tank completely. A tuning fork of $600\;Hz$ is vibrated and kept at the upper end of tube and tube in gradually raised out of water. The total number of resonances heard before when the tube comes out of water, taking $v = 330\;m/s$ :

asked Dec 19, 2018 by pady_1

0 answers

A 1.0 HP motor pumps out water from a well of 30 m and fills a water tank of volume 2238 litres at a height of 10 m from the ground. The running time of the motor to fill the empty water tank is :

asked Dec 19, 2018 by pady_1

0 answers

While a collector to emitter voltage is constant in a transistor, the collector current enhanges by $8.2\;mA$ when the emitter current changes by $8.3\;mA$. The value of forward current ratio is :

asked Dec 11, 2018 by pady_1

0 answers

If $\theta_i$ is the inversion temperature, $\theta_n$ is the neutral temperature, $\theta_c$ is the temperature of the cold junction then :

asked Dec 11, 2018 by pady_1

0 answers

Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon

asked Dec 11, 2018 by pady_1

0 answers

A particle is moving with a uniform speed in a circular orbit of radius R in a central force inversely proportional to the $n^{th}$ power of $R$. If the period of rotation of the particle is T, then :

asked Dec 11, 2018 by pady_1

0 answers

The integral $\begin{align} \int^{\frac{3\pi}{4}}_{\frac{\pi}{4}} \frac{dx}{1+ \cos x} \end{align}$ is equal to

asked Dec 11, 2018 by pady_1

1 answer

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

Diameter of a steel ball is measured using a Vernier callipers which has divisions of 0.1 cm on its main scale (MS) and 10 divisions of its vernier scale (VS) match 9 divisions on the main scale. Three such measurements for a ball are given as : If the zero error is 20.03 cm, then mean corrected diameter is :

asked Dec 11, 2018 by pady_1

0 answers

Assume that an electric field $\overrightarrow{E} = 30 x^2 \hat{i}$ exists in space. Then the potential difference $V_A - V_O$, where $V_O$ is the potential at the origin and $V_A$ the potential at $x=2$ is :

asked Dec 11, 2018 by pady_1

0 answers

In which of the following pairs of molecules/ions, both the species are not likely to exist?

asked Dec 11, 2018 by pady_1

0 answers

Let ABCD be a parallelogram such that $\overrightarrow{AB} = \overrightarrow{q}, \overrightarrow{AD} = \overrightarrow{p}$ and $\angle{BAD}$ be an acute angle. If $\overrightarrow{r}$ is the vector that coincides with the altitude directed from the vertex B to the side AD, then $\overrightarrow{r}$ is given by

asked Dec 11, 2018 by pady_1

0 answers

This question has Statement-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements. Statement-1 : A metallic surface is irradiated by a monochromatic light of frequency $v > v_0$ (the threshold frequency). The maximum kinetic energy and the stopping potential are $K_{max}$ and $V_0$ respectively. If the frequency incident on the surface doubled, both the $K_{max}$ and $V_0$ are also doubled. Statement-2 : The maximum kinetic energy and the stopping potential of photoelectrons emitted from a surface are linearly dependent on the frequency of incident light.

asked Dec 11, 2018 by pady_1

0 answers

For a particular reversible reaction at temperature $T, \Delta H$ and $\Delta S$ were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when

asked Dec 11, 2018 by pady_1

0 answers

The net work done on the gas in the cycle ABCDA is

asked Nov 29, 2018 by pady_1

0 answers

The area of the plane region bounded by the curves $x + 2y^2 = 0$ and $x + 3y^2 = 1$ is equal to

asked Nov 29, 2018 by pady_1

0 answers

Let $\overrightarrow{a} = \hat{i} + \hat{j} + \hat{k}, \overrightarrow{b} = \hat{i} - \hat{j} + 2 \hat{k}$ and $\overrightarrow{c} = x \hat{i} + ( x - 2)\hat{j} - \hat{k}$. If the vector $\overrightarrow{c}$ lies in the plane of $\overrightarrow{a}$ and $\overrightarrow{b}$, then $x$ equals :

asked Nov 29, 2018 by pady_1

0 answers

In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency $\omega$ in a magnetic field B. The maximum value of emf generated in the coil is :

asked Nov 13, 2018 by pady_1

0 answers

If $\cos^{-1} x- \cos^{-1} \frac{y}{2} = \alpha$, then $4x^2 - 4xy \cos \alpha + y^2$ is equal to :

asked Nov 5, 2018 by pady_1

0 answers

A Photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed $\frac{1}{2}m$ away, the number of electrons emitted by photocahode would :

asked Nov 5, 2018 by pady_1

0 answers

If $ \begin{align} x = e^{{y+e}^{^{y+...to\; \alpha}}}, \; x >0 \end{align}$, then $\frac{dy}{dx}$ is

asked Nov 5, 2018 by pady_1

0 answers

A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field $\overrightarrow{E}$. Due to the force q $\overrightarrow{E}$, its velocity increases from 0 to 6 m/s in one second duration. At that instant the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively

asked Aug 21, 2018 by pady_1

1 answer

Predict the correct intermediate and product in the following reaction : $H_3C - CH \equiv CH \xrightarrow[\text{$HgSO_4$}]{\text{$H_2O, H_2SO_4$}} \stackrel{\hbox{Intermediate}}{\hbox{(A)}} \to \stackrel{\hbox{Product}}{\hbox{(B)}}$

asked Aug 21, 2018 by pady_1

2 answers

Which of the following statements about the composition of the vapour over an ideal 1 : 1 molar mixture of benzene and toluene is correct ? Assume that the temperature is constant at $25^oC$. (Given, Vapour Pressure Data at $25^oC$, benzene = 12.8 kPa, toluene = 3.85 kPa)

asked Aug 21, 2018 by pady_1

1 answer

The following reaction is known by the name -

asked Aug 21, 2018 by pady_1

1 answer

In an ammeter 0.2% of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be:

asked Aug 20, 2018 by pady_1

1 answer

A bar magnet of length â€˜lâ€™ and magnetic dipole moment â€˜Mâ€™ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be â€“

asked Aug 20, 2018 by pady_1

1 answer

Four point charge –Q, –q, 2q and 2Q are placed, one at each corner of the square. The relation between Q and q for which the potential at the centre of the square is zero is

asked Aug 20, 2018 by pady_1

1 answer

During an isothermal expansion, a confined ideal gas does - 150 J of work against its surroundings. This implies that :

asked Aug 16, 2018 by pady_1

1 answer

The energy of a hydrogen atom in the ground state is – 13.6 eV. The energy of $He^{+}$ ion in the first excited state will be –

asked Jul 26, 2018 by pady_1

1 answer

The electric potential at a point (x, y, z) is given by $V=-x^{2}y-xz^{3}+4$, The electric field E at that point is :

asked Jul 26, 2018 by pady_1

1 answer

A boy is trying to start a fire by focusing Sunlight on a piece of paper using an equiconvex lens of focal length 10 cm. The diameter of the Sun is $1.39 \times 10^ 9$ m and its mean distance from the earth is $1.5 \times 10^{11}$ m. What is the diameter of the Sun’s image on the paper ?

asked Jul 26, 2018 by pady_1

1 answer

Three resistances P, Q, R each of $2 \Omega$ and an unknown resistance S form the four arms of a Wheatstone bridge circuit. When a resistance of $6 \Omega$ is connected in parallel to S the bridge gets balanced. What is the value of S ?

asked Jul 26, 2018 by pady_1

1 answer

The moment of inertia of a uniform circular disc of radius 'R' and mass 'M' about an axis touching the disc at its diameter and normal to the disc is:-

asked Jul 25, 2018 by pady_1

1 answer

Fission of nuclei is possible because the binding energy per nucleon in them-

asked Jul 24, 2018 by pady_1

1 answer

The half life of radium in about 1600 years. Of 100g of radium existing now, 25g will remain undecayed after :-

asked Jul 24, 2018 by pady_1

1 answer

An electric kettle has two heating coils. When one of the coils is connected to an a.c. source, the water in the kettle boils in 10 minutes. When the other coil is used the water boils in 40 minutes. If both the coils are connected in parallel, the time taken by the same quantity of water to boil will be :-

asked Jul 24, 2018 by pady_1

1 answer

If kinetic energy of a body is increased by 300% than percentage change in momentum will be

asked Jul 23, 2018 by pady_1

1 answer

On the horizontal surface of a truck a block of mass 1 kg is placed ($\mu = 0.6$) and truck is moving with acceleration $5 m/s^2$ then the frictional force on block will be :-

asked Jul 20, 2018 by pady_1

2 answers

The ratio (W/Q) for a carnot – engine is $\frac{1}{6}$ ,Now the temp. of sink is reduced by 62ºC, then this ratio becomes twice, therefore the initial temp. of the sink and source are respectively :

asked Jul 20, 2018 by pady_1

1 answer

When three identical bulbs are connected in series, the consumed power is 10W. If they are now connected in parallel then the consumed power will be :

asked Jun 15, 2018 by pady_1

1 answer

Vondra is sorting pencils into boxes. She put 8 pencils in the first box, 16 pencils in the second box, 24 pencils in the third box, and 32 pencils in the fourth box. If this pattern continues, how many pencils will Vondra put in the fifth box?

asked Dec 31, 2015 by pady_1

0 answers

Convert a distance of 20 km to metres.

asked Dec 31, 2015 by pady_1

0 answers

$\large\frac{12}{11} \div \large\frac{144}{121}$

asked Dec 31, 2015 by pady_1

0 answers

A student has to secure 33 \% of the maximum marks to pass. He secures 295 marks and fails by 200 marks. Find the maximum marks.

asked Dec 31, 2015 by pady_1

1 answer

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