Recent questions tagged class12

An electric line of force in the $xy$ plane is given by equation $x^2+y^2=1$. A particle with unit positive charge, initially at rest at the point $x = 1, y = 0$ in the $xy$ plane

asked Feb 27, 2014 by thanvigandhi_1

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The densities of NaCl crystal as measured by Spectrometer and X - ray method are $2.165\times10^3 kgm^{-3}$ and $2.178\times10^3 kgm^{-3}$, respectively . The fraction of unoccupied sites in sodium chloride crystal is

asked Feb 27, 2014 by sharmaaparna1

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If $c$ is the speed of electromagnetic waves in vacuum, their speed in a medium of dielectric constant $K$ and relative permeability $ \mu_r$ is

asked Feb 27, 2014 by thanvigandhi_1

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$CsBr$ crystallises in a body centered cubic lattice. The unit cell length is $436.6\; pm$ . Given that the atomic mass of $Cs = 133$ and of $Br = 80\; amu$. Avogadro's number being $6.02\times10^{23}mol^{-1}$ The density of $CsBr$ is

asked Feb 27, 2014 by sharmaaparna1

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A beam of light travelling along $ x$ - axis is described by the electric field $E_y = (600 V/m) \sin \omega (t - x/c)$ then maximum magnetic force on a charge $q = 2e$, moving along $y$ - axis with a speed of $3.0 \times 10^7m/s$ is $(e = 1.6 \times 10^{-19} C)$

asked Feb 27, 2014 by thanvigandhi_1

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Silver (atomic weight = $107.88$) crystallises with f.c.c lattice for which the side length of the unit cell is $4.0774\overset{\circ}{A}$. Density of $Ag$ is $10.53\; g\;cm^{-3}$. Calculate the Avogadro's number.

asked Feb 27, 2014 by sharmaaparna1

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A match box exhibits :

asked Feb 27, 2014 by sharmaaparna1

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About 5% of the power of a $100\: W$ light bulb is converted to visible radiation. What is the average intensity of visible radiation at a distance of $10\: m$ from the bulb?

asked Feb 27, 2014 by thanvigandhi_1

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The angle at which first order reflection will occur when X-ray of wavelength $1.54A^{\large\circ}$ are diffracted by the atoms of a crystal ; the interplanar distance is $4.04A^{\large\circ}$

asked Feb 27, 2014 by sharmaaparna1

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CsBr has b.c.c structure with edge length $4.3 A^{\large\circ}$. The shortest inter ionic distance between $Cs^+$ and $Br^-$ is

asked Feb 27, 2014 by sharmaaparna1

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A parallel plate capacitor of area $50\: cm^2$ and plate separation $3\: mm$ is charged initially to $80\: \mu C$. Due to a radioactive source nearby, the medium between the plates gets slightly conducting and the plate loses charge initially at the rate of $1.5 \times 10^{-8}C/s$. What is the magnitude and direction of displacement current?

asked Feb 27, 2014 by thanvigandhi_1

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Among O-nitro aniline(I),P-nitro aniline (II),M-nitro aniline (III) the order of increasing basic strength is

asked Feb 27, 2014 by sreemathi.v

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The correct sequence regarding base strength of aliphatic amines in gaseous phase is

asked Feb 27, 2014 by sreemathi.v

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A parallel plate capacitor with plate area $A$ and separation $d$ between the plates is charged by a constant current $i$. Consider a plane surface of area $A/4$ parallel to the plates and drawn symmetrically between the plates. Calculate the displacement current through this area.

asked Feb 27, 2014 by thanvigandhi_1

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The order of increasing basic strength among P-amino benzaldehyde(I),P-nitro aniniline (II) and P-bromo aniline (III) is

asked Feb 27, 2014 by sreemathi.v

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Find the energy of a photon in electron volt of microwaves having wavelength $3mm.(1\: eV = 1.6 \times 10^{-19}J)$

asked Feb 27, 2014 by thanvigandhi_1

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The number of resonating structures of below is

asked Feb 27, 2014 by sreemathi.v

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Light with an energy flux of $18\: W/cm^2$ surface has an area of $ 20\: cm^2$ falls on a non-reflecting surface at normal incidence. If the , the average force exerted on the surface during a $30$ minute time span is

asked Feb 27, 2014 by thanvigandhi_1

1 answer

The magnetic field in a plane electromagnetic wave is given by $B_y= 2 \times 10^{-7} \: \sin (0.5\times10^3x+1.5\times10^{11}t)T$ The wavelength and frequency of the wave are

asked Feb 27, 2014 by thanvigandhi_1

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Which of the following order is correct regarding the relative basicity of amines?

asked Feb 27, 2014 by sreemathi.v

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A plane electromagnetic wave of frequency $25\: MHz$ travels in free space along the $x$ - direction. At a particular point in space and time, $E= 6.3 \: jV/m$. What is B at this point?

asked Feb 27, 2014 by thanvigandhi_1

1 answer

In the following compounds the order of basicity is

asked Feb 27, 2014 by sreemathi.v

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The intensity of the sunlight reaching the earth is $1380\; W/m^2$. Calculate the amplitude of the magnetic field in the light wave. Assume the light to be a plane monochromatic wave.

asked Feb 27, 2014 by thanvigandhi_1

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Which reagent can provide distinction between aliphatic $-NH_2$ group and aromatic $-NH_2$ group?

asked Feb 27, 2014 by sreemathi.v

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The wavelength of a radio wave of frequency of $1\: MHz$ is:

asked Feb 27, 2014 by thanvigandhi_1

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Which of the following are not electromagnetic waves?

asked Feb 27, 2014 by thanvigandhi_1

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An isotope is radioactive . It is being produced at constant rate b . Half - life of radioactive substance is a . After some time no.of radioactive nuclei become constant . Then value of this constant is .

asked Feb 27, 2014 by yamini.v

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A radioactive material of Lay life T was produced in a nuclear reactor at different instants , the quantity produced second time was twice of that produced first time . If now their present activities are $\;A_{1}\;$ and $\;A_{2}\;$ respectively . Then their age difference equals :

asked Feb 27, 2014 by yamini.v

1 answer

In the below reaction,the reactive intermediate formed is

asked Feb 27, 2014 by sreemathi.v

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What would be the reagent in the below reaction

asked Feb 27, 2014 by sreemathi.v

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The radii of two nuclei with atomic ratio of no .1 & 27 is ?

asked Feb 27, 2014 by yamini.v

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Which of following are not deflected by a magnetic field ?

asked Feb 27, 2014 by yamini.v

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In the below reaction P is

asked Feb 27, 2014 by sreemathi.v

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What would be the major product on the following reaction?

asked Feb 27, 2014 by sreemathi.v

1 answer

Mark the correct option

asked Feb 27, 2014 by thanvigandhi_1

1 answer

Which of the following statement is correct?

asked Feb 27, 2014 by sreemathi.v

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S1: Faraday’s Law of electromagnetic induction is induced emf, $e = \large\frac{-d \phi }{dt}$ \[\] S2: Due to changing magnetic field, if $E$ is induced electric field, then $e = \int E \: dl$ \[\] S3: From above two statements, $ \int E\: dl =\large\frac{-d \phi }{dt}$

asked Feb 27, 2014 by thanvigandhi_1

1 answer

A new carbon-carbon bond formation is possible in

asked Feb 27, 2014 by sreemathi.v

1 answer

Relative permittivity and permeability of a material are $ \in_r$ and $ \mu_r$ , respectively. Which of the following values of these quantities are allowed for a diamagnetic material?

asked Feb 27, 2014 by thanvigandhi_1

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What would be the product in the below reaction:

asked Feb 27, 2014 by sreemathi.v

1 answer

A neutron moving with speed V makes a head on collision with a hydrogen atom in ground state kept at a rest. Then find the minimum kinetic energy of neutron for which inelastic (completely of partially ) collision may take place . (mass of neutron =mass of hydrogen =$\;1.67\times10^{-27} Kg$) .

asked Feb 27, 2014 by yamini.v

1 answer

The nuclear reaction $\;n + _{5}^{10}B \to _{3}^{7}{Li}+_{2}^{4}He\;$ is observed to occur when very slow - moving neutrons $\;(M_{n}=1.0087 u)\;$ strike a boron atom at rest . For a particular reaction in which $\;K_{n} \approx 0\;,$ the helium $\;(M_{He}=4.0026 u)\;$ is observed to have a speed of $\;9.30\times 10^{6} m/s\;.$ Then the kinetic energy of $\;(lithium\;M_{li}=7.016 u)\;$. Find Q value of reaction .

asked Feb 27, 2014 by yamini.v

1 answer

Some radio waves of frequency of about $1.5 \times 10^9\: Hz$ was received by a radio-telescope from distant star. If the speed of the waves is $3 \times 10^5\: km/s$ , then the wave- length of the wave will be:

asked Feb 27, 2014 by thanvigandhi_1

1 answer

Electromagnetic waves are transverse in nature is evident by

asked Feb 27, 2014 by thanvigandhi_1

2 answers

What could be the major product in the below reaction

asked Feb 27, 2014 by sreemathi.v

1 answer

The nuclear reaction $\;n + _{5}^{10}B \to _{3}^{7}{Li}+_{2}^{4}He\;$ is observed to occur when very slow - moving neutrons $\;(M_{n}=1.0087 u)\;$ strike a boron atom at rest . For a particular reaction in which $\;K_{n} \approx 0\;,$ the helium $\;(M_{He}=4.0026 u)\;$ is observed to have a speed of $\;9.30\times 10^{6} m/s\;.$ Then the kinetic energy of $\;(lithium\;M_{li}=7.016 u)\;$

asked Feb 27, 2014 by yamini.v

1 answer

Phenol undergoes condensation with acetaldehyde in acidic (or) alkali medium gives

asked Feb 27, 2014 by sreemathi.v

1 answer

In chain analysis of a rock , the mass ratio of two radioactive isotope is found to be $\;100 \%\;$ . The mean lives of two isotopes are $\;4 \times 10^{9}\;$years and $\;2\times10^{9}\;$years respectively . If it is assumed that at time of formation of rock , both isotopes were in equal proportion . Then calculate age of rock . Ratio of atomic weights of two isotope is $\;1.02 \%\;(log_{10}^{1.02}=0.0086)$

asked Feb 27, 2014 by yamini.v

1 answer

Phenol on exposure to air produces

asked Feb 27, 2014 by sreemathi.v

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In the following compounds

asked Feb 27, 2014 by sreemathi.v

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