Question

Consider the following statements:
$A.$ Atoms of each element emit characteristics spectrum.
$B.$ According to Bohr's Postulate, an electron in hydrogen atom, revolves in a certain stationary orbit.
$C.$ The density of nuclear matter depends on the size of the nucleus.
$D.$ A free neutron is stable but a free proton decay is possible.
$E.$ Radioactivity is an indication of the instability of nuclei.
Choose the correct answer from the options given below

• A. $A,B,C,D\text{and}E$
• B. $A,B\text{and}E\text{only}$
• C. $B\text{and}D\text{only}$
• D. $A,C\text{and}E\text{only}$

Answer 1

The correct option is B $A,B\text{and}E\text{only}$

$\left(A\right)$ True, atom of each element emits characteristic spectrum.
$\left(B\right)$ True, according to Bohr's Postulate,
$mvr=\frac{nh}{2\pi }$ and hence electron resides into orbits of specific radius called stationary orbits.
$\left(C\right)$ False, densityof nucleus is constant.
$\left(D\right)$ False, a free neutron is unstable, decays into proton and electron and antineutrino.
$\left(E\right)$ True, ustable nucleus shows radioactivity.