Question

$\beta $ -particle is emitted in radioactivity by:
A. Conversion of proton to neutron
B. From outermost orbit
C. Conversion of neutron to proton
D. Conversion of electron to proton

Answer 1

Hint: Radioactivity is a property of radioactive substance. Radioactive substance undergoes several modes of decay to make the radioactive nucleus stable. The radioactive nuclides undergo decay to give alpha, beta, gamma, X-rays. All this rays have different energy, different characteristics.

Complete Step by Step Solution:
$\beta $ -rays consist of beta particles. The beta particles are actually high energetic electrons. Electrons are negatively charged particles of the nucleus that revolve around the nucleus. Due to the presence of positively charged protons in the nucleus an atom remains stable with negatively charged electrons.

During radioactive decay a radioactive nucleus beta particle and then neutron of the nucleus is internally converted into a proton and one particle called antineutrino which has zero mass and zero charge is emitted to balance the law of conservation of mass.
The reaction of emission of beta particle from a radioactive nucleus can be given as follows-
${}_{0}^{1}n\to {}_{1}^{1}p+{{e}^{-}}+\gamma {}_{0}^{0}$
Thus the correct option is C.

Note: The modes of decay of a radioactive nucleus can be determined by neutron to proton ratio of the nucleus. If the neutron to proton ratio lies above the stability zone then the nucleus shows beta particle emission and a neutron is internally converted to a proton to decrease the neutron to proton ratio.