1
WB JEE 2020
+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
+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
+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 2017
+1
-0.25 When light of frequency v1 is incident on a metal with work function W (where hv1 > W), then photocurrent falls to zero at a stopping potential of V1. If the frequency of light is increased to v2, the stopping potential changes to V2. Therefore, the charge of an electron is given by
A
$${{W({v_2} + {v_1})} \over {{v_1}{V_2} + {v_2}{V_1}}}$$
B
$${{W({v_2} + {v_1})} \over {{v_1}{V_1} + {v_2}{V_2}}}$$
C
$${{W({v_2} - {v_1})} \over {{v_1}{V_2} - {v_2}{V_1}}}$$
D
$${{W({v_2} - {v_1})} \over {{v_2}{V_2} - {v_1}{V_1}}}$$
WB JEE Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
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