Part Test- 6 (JEE Main 2018) - JEE MCQ

No. of identical photons incident on a perfectly black body of mass m kept at rest on smooth horizontal surface. Then the acceleration of the body if n number of photons incident per second is (Assume wavelength of photon to be λ) :

If we assume that penetrating power of any radiation/particle is inversely proportional to wavelength of the particle then :            

Two radioactive sources A and B initially contain equal number of radioactive atoms. Source A has a half-life of 1 hour and source B has a half-life of 2 hours. At the end of 2 hours, the ratio of activity of source A to that of B is : 

The radionuclide 238U decays by emitting an alpha particle.    

What is the maximum kinetic energy of the emitted alpha particle? Express your answer in Joule. 

(1amu =1.67 x 10^-27 kg)

Choose the correct statement.        

A beam of electrons striking a copper target produces X-rays.Its spectrum is as shown. Keeping the voltage same if the copper target is replaced with a different metal, the cut-off wavelength and characteristic lines of the new spectrum will change in comparision with old as :    

Both the frequency and the intensity of a beam of light falling on the surface of photoelectric material are increased by a factor of two. This will :            

The photon radiated from hydrogen corresponding to 2^nd line of Lyman series is absorbed by a hydrogen like atom ‘X’ in 2^nd excited state. As a result the hydrogen like atom ‘X’ makes a transition to n^th orbit. Then,

The angular momentum of an electron in first orbit of Li⁺⁺ ion is :    

An electron is accelerated through a potential difference of V volt. It has a wavelength λassociated with it. Through what potential difference must an electron be accelerated so that its de-Broglie wavelength is the same as that of a proton? Take mass of a proton to be 1837 times larger than the mass of electron.

Two hydrogen atoms are in excited state with electrons residing in n = 2. First one is moving towards left and emits a photon of energy E₁ towards right. Second one is moving towards left with same speed and emits a photon of energy E₂ towards left. Taking recoil of nucleus into account during emission process

In a hydrogen atom following the Bohr’s postulates the product of linear momentum and angular momentum is proportional to (n)^x where ‘n’ is the orbit number. Then ‘x’ is :

One of the lines in the emission spectrum of Li²⁺ has the same wavelength as that of the 2^nd line of Balmer series in hydrogen spectrum. The electronic transition corresponding to this line is :

The ratio of wave length of a photon of energy E and deBroglie wavelength of an electron of mass 'm' having the kinetic energy also E is : (Speed of light = c)         

An orbital electron in the ground state of hydrogen has an angular momentum L₁ and an orbital electron in the first orbit in the ground state of lithium (double ionised positively charged) has an angular momentum L₂ .Then :

If in the first orbit of a hydrogen atom the total energy of the electron is -21.76 x 10^-19J, then its electric potential energy will be :

In an x - ray tube, if the accelerating potential difference is changed, then:      

All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before travelling 1 m in the direction of uniform electric field of 4 N/C. The work function of the surface is:

The energy ratio of two K_α  photons obtained in x-ray from two metal targets of atomic numbers Z₁ and Z₂ is:                                        

A cobalt (atomic no. = 27) target is bombarded with electrons, and the wavelengths of its characteristic x-ray spectrum are measured. A second weak characteristic spectrum is also found, due to an impurity in the target. The wavelengths of the K_α lines are 225.0 pm (cobalt) and 100.0 pm (impurity).  Atomic number of the impurity is (take b = 1)

A hydrogen atom is in the 4th excited state, then:

In the photoelectric experiment, if we use a monochromatic light, the I - V curve is as shown. If work function of the metal is 2eV, estimate the power of light used. (Assume efficiency of photo emission = 10^–3%, i.e. number of photoelectrons emitted are 10^–3% of number of photons incident on metal.)

If first excitation potential of a hydrogen like atom is V volt, then the ionization energy of this atom will be :

The element which has a ka  x-rays line of wavelength 1.8 Å is     (R =1.1 x 10⁷ m-1 , b=1 and   = 0.39)

The radii of nuclei of two atoms are in ratio 3/2 . Assuming them to be Hydrogen like atom, the ratio of their orbital radius for K shell will be (assume no. of proton = No. of neutron for each atom)     

A radioactive nucleus can decay by either emitting an α particle or by emitting a β particle. Probability of α decay is 75% while that of β decay is 25%. The decayconstant of α  decay  is λ₁ and that of b decay is λ₂ .  is

A radioactive nucleus ' X ' decays to a stable nucleus ' Y '. Then the graph of rate of formation of ' Y' against time ' t ' will be :