Recent questions tagged ch-5

Explain how the phenomenon of absorption finds application in each of the following process : (i) Production of vaccum (ii) Heterogeneous catalysis

asked Nov 25, 2016 by meena.p

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Dialysis is a method of purification of sols, But prolonged dialysis of the sol makes it unstable . Why ?

asked Nov 23, 2016 by meena.p

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Decomposition of phosphine $(PH_3)$ at $120^{\circ}C$ proceeds according to the equation: $4PH_3(g) \to P_4(g) + 6H_2(g)$ It is found that this reaction follows the following rate equation: Rate $= k[PH_3]$ The half-life of $PH_3$ is $37.9\;s$ at $120^{\circ}C.$ (i) How much time will be required for $\large\frac{3}{4}$ of $PH_3$ to decompose? (ii) What fraction of the original amount of $PH_3$ will remain undecomposed after 1 minute?

asked Nov 22, 2016 by meena.p

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On visit to your native village, you find that lot of smoke, dust and some other gases are coming out of the chimney of a recently set up factory near the village which is the cause of many respiratory problems for the people living there. Answer the following questions (i) As a chemistry student, what method you will suggest the factory owner to manage dust and smoke? (ii) What is the basic principle involved in your suggestion? (iii) What values are associated with your advice?

asked Nov 22, 2016 by meena.p

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$SnO_2$ forms a positively charged colloidal Sol in the basic medium why ?

asked Nov 22, 2016 by meena.p

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Write two difference between sols and emulsions.

asked Nov 17, 2016 by meena.p

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Explain : (i) The molecules $NH_3$ and $NF_3$ have dipole moments which are of opposite direction . (ii) Sulphur in vapour state exhibits paramagnetism

asked Nov 17, 2016 by meena.p

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What is observed when : (i) A beam of light is passed through a colloidal solution ? (ii) Electric current is passed through a colloidal solution ?

asked Nov 16, 2016 by meena.p

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Why is ferric chloride preferred over potassium chloride in case of a cut leading to bleeding?

asked Nov 14, 2016 by meena.p

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Differentiate w . r . t x $\tan^{-1}\bigg[\large\frac{1-\cos x}{sin x}\bigg]; -\pi < x < \pi$

asked Nov 10, 2016 by priyanka.c

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Depict the galvanic cell in which the reaction $2Zn(s) +2 Ag^{+}(aq) \to Zn ^{2+}(aq) +2 Ag(s) $ takes place . Further show: (i) Which of the electrode is negatively charged? (ii) The carriers of the current in the cell. (iii) Individual reaction at each electrode.

asked Nov 4, 2016 by meena.p

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Why is ferric chloride preffered over potassium in case of a cut leading to bleeding ?

asked Nov 4, 2016 by meena.p

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Explain what is observed when (a) an electric current is passed through a solution . (b) a beam of light is passed through a solution (c) an electrolyte (say NaCl) is added to ferric hydroxide solution .

asked Nov 3, 2016 by meena.p

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What is the main cause of charge on a colloidal solution ?

asked Oct 31, 2016 by meena.p

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Out of C and CO, which is a better reducing agent for ZnO ?

asked Oct 27, 2016 by meena.p

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Give one example each of oil in water and water in oil emulsion.

asked Oct 25, 2016 by meena.p

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Why does a galvanic cell become dead after some time ?

asked Oct 25, 2016 by meena.p

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Why does physiorption decrease with increase of temperature ?

asked Oct 20, 2016 by meena.p

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On dissolving $19.5\;g$ of $CH_2FOOH$ in $500\;g$ of water, a depression of $1^{\circ}C$ in freezing point of water is observed . Calculate the van't Hoff factor and dissociation constant of fluoro acetic acid Given $K_f= 1.86\;k kg mol^{-1}$

asked Oct 20, 2016 by meena.p

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Copper can be extracted by hydro metallurgy but not zinc. Explain .

asked Oct 17, 2016 by meena.p

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Absorption of gases on solid surface is generally exothermic because absorption

asked Oct 13, 2016 by meena.p

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For a para magnetic substance

asked Jul 22, 2015 by meena.p

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The magnetic susceptibility of a super conductor is __________

asked Jul 22, 2015 by meena.p

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The susceptibility of magnetism at book is $ 1.2 \times 10^{-5}$ At what temperature will the susceptibility be equal to $1.44 \times 10^5?$

asked Jul 22, 2015 by meena.p

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A circular coil of $300$ turns and diameter 14 cm carries a current of $15\;A$ . What is the magnitude of magnetic moment associated with the coil ?

asked Jul 22, 2015 by meena.p

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Iso gonic lines are the lines joining places of ____________

asked Jul 22, 2015 by meena.p

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The small angle between magnetic axis and geographic axis at a place is called _________ at that place .

asked Jul 22, 2015 by meena.p

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The value of H on the surface of earth is of the order of ___________

asked Jul 22, 2015 by meena.p

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A freely suspended magnet at equator will set itself _________ to the surface of earth

asked Jul 22, 2015 by meena.p

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If $\lambda$ is the magnetic latitude at a place, then what is the relation between the angle of dip and $\lambda$ magnetic latitude .

asked Jul 22, 2015 by meena.p

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A short bar magnet is placed with its north pole pointing south . The natural point is $15\;cm$ away from the center of the magnet. If $H= 0.5 \;G$, Calculate the magnetic moment of the magnet.

asked Jul 22, 2015 by meena.p

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In a tangent galvanometer , When a current of $10\;mA$ is passed the deflection is $31^{\circ}$ By what percentage , the current has to be increased , so as to produce a deflection of $42^{\circ}$?

asked Jul 22, 2015 by meena.p

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In a magnetic of a certain place, the horizontal component of the earth magnetic field is $0.26 \;G$ and dip angle is $60^{\circ}$ What is the magnetic field of earth at this location ?

asked Jul 22, 2015 by meena.p

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Two identical thin bar magnets, each of length L and pole strength m are placed at right angles to each other, with the north pole of one touching the south pole of the other . Find the magnetic moment of the system.

asked Jul 21, 2015 by meena.p

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A magnetized steel wire $31.4\;cm$ long has pole strength of $0.2 \;Am$ It is then bent in the form of a semicircle. Calculate the magnetic moment of the needle.

asked Jul 21, 2015 by meena.p

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A compass needle whose magnetic moment is $60Am^2$ pointing geographic north at a certain place, Where the horizontal component of earth's magnetic field is $40 \mu wbm^{-2}$ experiences a torque $1.2 \times 10^{-3}\;Nm$ What is the declination of the place?

asked Jul 21, 2015 by meena.p

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The declination at a place is $20^{\circ}$ west. In what direction should a ship be stressed so that it reaches geographic north east ?

asked Jul 21, 2015 by meena.p

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What is the approximate distance upto which earth's magnetic field extends?

asked Jul 21, 2015 by meena.p

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A magnetic dipole is situated in the direction of a magnetic field . What is its potential energy ?

asked Jul 21, 2015 by meena.p

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Give two examples of magnetic dipole

asked Jul 21, 2015 by meena.p

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Why do magnetic lines of force prefer to pass through ferromagnetic substance than through air ?

asked Jul 21, 2015 by meena.p

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Name the material used in making the core of moving coil galvanometer .

asked Jul 21, 2015 by meena.p

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An electron and a proton equal momenta, enter a uniform magnetic field at right angles to the field lines. What will be the ratio of the radii of an vature of there trajectories .

asked Jul 21, 2015 by meena.p

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The earth's field departs from its dipole shape substantially at large distance (greater than about 30,000 km) What agencies may be responsible for this distortion ?

asked Jul 21, 2015 by meena.p

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Why do we prefer steel or alnico for making permanent magnets ?

asked Jul 21, 2015 by meena.p

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A coil of 200 turns has a cross -sectional area $900 mm^2$ . if carries a current of 2 ampere . The plane of the coil is perpendicular to a uniform magnetic field of $0.5 \;T$ Calculate the magnetic moment of the coil.

asked Jul 21, 2015 by meena.p

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State curies's law in magnetism?

asked Jul 21, 2015 by meena.p

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A magnetic needle of magnetic moment $4.8 \times 10^{-2}\;JT^{-1}$ is placed at $30^{\circ}$ with the direction of uniform magnetic field of magnitude $3 \times 10^{-2} \;T$ Calculate the torque acting on the needle

asked Jul 21, 2015 by meena.p

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A magnetized needle is placed $30^{\circ}$ with direction of uniform magnetic field of intensity $3 \times 10^{-2}\;T$ The torque acting on the needle is $7.2 \times 10^{-4} \;J$ Calculate the magnetic moment of the needle .

asked Jul 20, 2015 by meena.p

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The vertical component of earth magnetic field at a plane is $\large\frac{1}{\sqrt 3}$ times the horizontal component. What is the value of angle of dip at this place ?

asked Jul 20, 2015 by meena.p

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