Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202127 JulyEvening Shift
Exam
JEE Main
Year
2021
Date
27 July
Shift
Evening Shift
Subject
Physics
Chapter
Nuclear Physics

JEE Main 2021 · 27 July · Evening Shift · Physics · Nuclear Physics

Consider the following statements: A . Atoms of each element emit...

Consider the following statements:
AA. Atoms of each element emit characteristics spectrum.
B.B . According to Bohr's Postulate, an electron in a hydrogen atom revolves in a certain stationary orbit.

C.C . The density of nuclear matter depends on the size of the nucleus.
D.D . A free neutron is stable but a free proton decay is possible.
E.E . Radioactivity is an indication of the instability of nuclei. Choose the correct answer from the options given below.

Options

  1. AA,B,C,DA, B, C, D and EE
  2. BA,BA, Band EE only.
  3. CBB and DD only
  4. DA,CA, C and EE only

Correct answer

B. A,BA, Band EE only.

Step-by-step solution

(A)( A ) True, an atom of each element emits a characteristic spectrum.

(B)( B ) True, according to Bohr's postulates mvr=nh2πmvr = \dfrac{nh}{2\pi} and hence electron resides into orbits of specific radius called stationary orbits.

(C)( C ) False, the density of the nucleus is constant.

(D)( D ) False, A free neutron is unstable decays into proton and electron and antineutrino.

(E)( E ) True unstable nucleus show radioactivity.

Practice Nuclear Physics on Quantrex Academy →

More from Nuclear Physics

A nuclear reactor starts producing a radioactive nuclide X from t = 0 , at a constant… JEE Advanced 2026Two radioactive substances A and B of mass numbers 200 and 212 respectively, shows… JEE Main 2026The energy released if hydrogen atoms are combined to form ^ 4 _ 2 He is __________ MeV.… JEE Main 2026The energy released when (7)/(17.13) kg of ^ 7 _ 3 Li is converted into ^ 4 _ 2 He by… JEE Main 2026Assuming the experimental mass of ^ 12 _ 6 C as 12 u , the mass defect of ^ 12 _ 6 C atom… JEE Main 2026Two nuclei of mass number 3 combine with another nucleus of mass number 4 to yield a… JEE Main 2026The binding energy per nucleon of ^ 209 _ 83 Bi is _______ MeV. [Take m(^ 209 _ 83 Bi) =… JEE Main 2026A nucleus has mass number α and radius R_ α . Another nucleus has mass number β and… JEE Main 2026 Full Nuclear Physics list All JEE Main PYQs