1
WB JEE 2020
MCQ (Single Correct Answer)
+1
-0.25
A nucleus X emits a $$\beta $$-particle to produce a nucleus Y. If their atomic masses are Mx and My respectively, then the maximum energy of the $$\beta $$-particle emitted is (where, me is the mass of an electron and c is the velocity of light)
A
$$({M_x} - {M_y} - {m_e}){c^2}$$
B
$$({M_x} - {M_y} + {m_e}){c^2}$$
C
$$({M_x} - {M_y} ){c^2}$$
D
$$({M_x} - {M_y} - {2m_e}){c^2}$$
2
WB JEE 2020
MCQ (Single Correct Answer)
+1
-0.25
For nuclei with mass number close to 119 and 238, the binding energies per nucleon are approximately 7.6 MeV and 8.6 MeV, respectively. If a nucleus of mass number 238 breaks into two nuclei of nearly equal masses, what will be the approximate amount of energy released in the process of fission?
A
214 MeV
B
119 MeV
C
2047 MeV
D
1142 MeV
3
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
A parent nucleus X undergoes $$\alpha$$-decay with a half-life of 75000 yrs. The daughter nucleus Y undergoes $$\beta$$-decay with a half-life of 9 months. In a particular sample, it is found that the rate of emission of $$\beta$$-particles is nearly constant (over several months) at $${10^7}/h$$. What will be the number of $$\alpha$$-particles emitted in an hour?
A
102
B
107
C
1012
D
1014
4
WB JEE 2019
MCQ (Single Correct Answer)
+1
-0.25
A proton and an electron initially at rest are accelerated by the same potential difference. Assuming that a proton is 2000 times heavier than an electron, what will be the relation between the de Broglie wavelength of the proton ($$\lambda$$p) and that of electron ($$\lambda$$e)?
A
$$\lambda = 2000{\lambda _e}$$
B
$${\lambda _p} = {{{\lambda _e}} \over {2000}}$$
C
$${\lambda _p} = 20\sqrt 5 {\lambda _e}$$
D
$${\lambda _p} = {{{\lambda _e}} \over {20\sqrt 5 }}$$
WB JEE Subjects