A ≥ Z [Equality sign → hydrogen nuclear]
The mass number of a nucleus is:
Held on 30 Apr 2003 · Verified 9 Jul 2026.
always less than its atomic number
always more then its atomic number
sometimes equal to its atomic number
sometimes less than and sometimes more than its atomic number
Sign in to track your attempts and accuracy.
Sign in to keep a private note on this question. Nothing you write is ever public.
De-Broglie wavelength of an electron orbiting in the $n=2$ state of hydrogen atom is close to (Given Bohr radius $=0.052 \mathrm{~nm}$ )
Which of the following options represent the variation of photoelectric current with property of light shown on the x -axis? 
The maximum kinetic energy of photoelectrons from a surface with work function φ = 2 eV when light of λ = 4000 Å falls on it is (hc = 12400 eV·Å):
A full wave rectifier circuit with diodes $\left(D_1\right)$ and $\left(D_2\right)$ is shown in the figure. If input supply voltage $V_{\text {in }}=220 \sin (100 \pi t)$ volt, then at $t=15 \mathrm{msec}$ 
A particle of mass $m$ is moving around the origin with a constant force $F$ pulling it towards the origin. If Bohr model is used to describe its motion, the radius $r$ of the $n^{\text {th }}$ orbit and the particle's speed $v$ in the orbit depend on $n$ as
Work through every NEET UG Modern Physics PYQ, year by year.