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limits

by shahil M -

lim x tends to 0             2x-sin^-1x

                                   2x+tan^-1x   

 pls someone do this question without expanding.

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Trigonometrical Ratios And Identities

by Anshul Chanchlani -

Prove That

sinx/cos3x +  sin3x/cos9x + sin9x/cos27x = 1/2 (tan27x-tanx)

Please reply with solution

Thankyou!

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Atomic Structure

by Anshul Chanchlani -

Calculate the wavelength of an electron that has been accelerated in a particle accelerator through a potential difference of 100 million volts.

How should I proceed in this.

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Atomic Structure : Where I am wrong?

by Anshul Chanchlani -

  The Kinetic energy of a sub-atomic particle is 5.65 * 10-25 J. Calculate the frequency of the particle wave.

Ans. K.E. = 5.65 * 10-25 J

       K.E.= 0.5 mv2

       v2 =   2 K.E. / m   , v = 1.11 *103 ms-1

       Wavelength = h / mv   

            c /frequency = h /mv where c = speed of light

         frequency = cmv/h

        But on putting values the answer does not match with the given answer that is 1.705 *10-9 s-1 .

So what is the correct solution?

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Significant figures pi

by Tanvi Mehta -

What value of pi should be taken in significant figures calculations?I guess it is a sure number.

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optics

by Divya Bhargavi -
a short linear object of length "b" lies along the principal axis of a concave mirror of focal length "f" at a distance 'u' from the pole of the mirror.What is the size of the image?
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Atomic Structure

by Anshul Chanchlani -

 Please reply to these problems with solution.

1. Calculate the wavelength of the radiations in nanometers emitted when  an electron in hydrogen atom jumps from third orbit to the ground state. (Rydberg's constant = 109677 cm-1  ).          [Ans. 103 nm]

2. Calulate the wavelength of proton which will be emitted when the electron of hydrogen atom jumps from fourth shell to the first shell. Ionisation energy of hydrogen atom is 1.312 * 103 kJ mol-1 . [Ans. 9.725 *10-8]

3. The ionisation energy of He+ ion is 19.6 * 10-18 J atom-1. Calculate the energy of the first excited state of Li2+ ion.  [Ans. -4.41 * 10-17 J atom-1]

Thank You

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Stoichiometry

by Mohit Tiwari -
How much BaCl2 would be needed to make 250 ml of a solution having same concentration of Cl- as the one containing 3.78 g of NaCl per 100 ml?
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