Recent questions in Chemistry

The binding energy of electrons in a metal is 250KJ/mol.What is the threshold frequency of metal ?

asked Jan 17, 2014 by sreemathi.v

1 answer

Wavelength of the $K_{\alpha}$ characteristic X-rays of iron and potassium are $1.93\times 10^{-8}$ are $3.737\times 10^{-8}cm$ respectively.What is the atomic number and name of the element for which characteristic $K_{\alpha}$ wavelength is $2.289\times 10^{-8}cm$ .

asked Jan 17, 2014 by sreemathi.v

1 answer

The minimum energy required to overcome the attractive forces between electron and the surface of Ag metal is $7.52\times 10^{-19}J$ .What will be the maximum kinetic energy of electron ejected out from Ag.Which is being exposed to uv light of $\lambda=360A^{\large\circ}$ ?

asked Jan 17, 2014 by sreemathi.v

1 answer

Calculate the uncertainty in velocity of a cricket ball (mass=0.15Kg) if its uncertainty in position is of the order of $1A^{\large\circ}$

asked Jan 17, 2014 by sreemathi.v

1 answer

Energy required to stop the ejection of electrons from $Cu$ plate is 0.24eV.Calculate the work function when radiations of $\lambda=253.7nm$ strikes the plate.

asked Jan 17, 2014 by sreemathi.v

1 answer

An electron has a total energy of 2MeV.Calculate the effective mass of the electron in Kg and its speed .Assume rest mass of electron 0.511MeV

asked Jan 16, 2014 by sreemathi.v

1 answer

Two hydrogen atoms collide head on and end up with zero kinetic energy.Each atom then emits a photon of wavelength 121.6nm.Which transition leads to this wavelength ?How fast were the hydrogen atoms traveling before collision? $R_H=1.097\times 10^7m^{-1}$ and $m_H=1.67\times 10^{-27}Kg$

asked Jan 16, 2014 by sreemathi.v

1 answer

With what velocity must an electron travel so that its momentum is equal to that of a photon of wavelength $\lambda=5200A^{\large\circ}$ ?

asked Jan 16, 2014 by sreemathi.v

1 answer

Calculate momentum of radiations of wavelength 0.33nm

asked Jan 16, 2014 by sreemathi.v

1 answer

Calculate the angular frequency of an electron occupying the second Bohr's orbit of $He^+$ ion.

asked Jan 16, 2014 by sreemathi.v

1 answer

Find the quantum no 'n' corresponding to the excited state of $He^+$ ion if on transition to the ground state that ion emits two photons in succession with wavelength 108.5 and 30.4nm

asked Jan 16, 2014 by sreemathi.v

1 answer

Calculate the wavelength emitted during the transition of electron in between two levels of $Li^{+2}$ ion whose sum is 4 and difference is 2.

asked Jan 16, 2014 by sreemathi.v

1 answer

A stationary $He^+$ ion emitted a photon corresponding to the first line $(H_{\alpha})$ of the Lyman series .That photon liberated a photo electron from a stationary H atom in ground state.What is the velocity of photo electron? $R_H=109678cm^{-1}$

asked Jan 16, 2014 by sreemathi.v

1 answer

The angular momentum of an electron in a Bohr's orbit of H-atom is $4.2178\times 10^{-34}Kg-m^2/s$ .Calculate the spectral line emitted when electron falls from this level to next lower level.

asked Jan 16, 2014 by sreemathi.v

1 answer

Calculate the uncertainty in velocity of a cricket ball (mass=0.15Kg) if its uncertainty position is of the order of $1A^{\large\circ}$

asked Jan 16, 2014 by sreemathi.v

1 answer

The vapours of Hg absorb some electrons accelerate by a potential difference of 4.5volts as a result of which light is emitted .If the full energy of single incident electron is supposed to be converted into light emitted by single Hg atom,find the wave number $\big(\large\frac{1}{\lambda}\big)$ of the light.

asked Jan 16, 2014 by sreemathi.v

1 answer

An electron beam can undergo diffraction by crystals.Through what potential should a beam of electrons be accelerated so that its wavelength becomes equal to $1.54A^{\large\circ}$ ?

asked Jan 16, 2014 by sreemathi.v

1 answer

Energy of the electron in H-atom is 1.50 times as much as energy as the minimum required for its escape (13.6eV) from the atom.Calculate the wavelength of the emitted electron.

asked Jan 16, 2014 by sreemathi.v

1 answer

When a certain metal was irradiated with light of frequency $1.6\times 10^{16}Hz$ ,the photoelectrons emitted had twice the kinetic energy as did photoelectrons emitted when the same metal was irradiated with light of frequency $1.0\times 10^{16}$ Hz.Calculate $V_0$ (threshold frequency) for the metal.

asked Jan 16, 2014 by sreemathi.v

1 answer

What electron transition in a hydrogen atom,starting from the orbit $n=7$ will produce infrared light of wavelength 2170nm?( $R_H=1.09677\times 10^7m^{-1})$

asked Jan 16, 2014 by sreemathi.v

1 answer

If uncertainties in the measurement of position and momentum are equal,calculate uncertainty in the measurement of velocity.

asked Jan 16, 2014 by sreemathi.v

1 answer

One quantum is absorbed per molecule of gaseous iodine for converting into iodine atoms.If light absorbed has wavelength of $5000A^{\large\circ}$ ,calculate energy required in KJ/mol.

asked Jan 16, 2014 by sreemathi.v

1 answer

Three isotopes of an element have mass numbers m,m+1 and m+2.If the mean mass number is ( m +0.5) then which of the following ratios may be accepted for m,(m+1) and (m+2) in that order

asked Jan 16, 2014 by sreemathi.v

1 answer

Calculate the uncertainty in velocity of an electron if uncertainty in its position is of the order of $1A^{\large\circ}$

asked Jan 16, 2014 by sreemathi.v

1 answer

An electron moves in an electric field with a kinetic energy of 2.5eV.What is the associated De-Broglie wavelength?

asked Jan 16, 2014 by sreemathi.v

1 answer

Calculate the accelerating potential that must be imparted to a proton beam to give it an effective wavelength of 0.005nm.

asked Jan 16, 2014 by sreemathi.v

1 answer