Question

${{C}^{14}}$ is:-
a. a natural non-radioactive isotope.
b. an artificial non-radioactive isotope
c. an artificial radioactive isotope
d. a natural radioactive isotope

Answer 1

To find the solution to above problem we have to study about the element carbon and its isotopes, all about their existing forms primarily; physical and chemical properties to have a good comparison to consider.

Complete Step by Step solution:
Carbon; with atomic no. 06 has mass of $12g$. In the modern periodic table it is placed in graph $14$ with the valency $4$and period $2.$
Till now $15$ isotopes of carbon are known having atomic mass $8,9,10,11,12,13,14,15,16,17,18,19,20,21,$ and $22$.
Out of all of these atomic masses $12$ and $13$ are more stable so they cannot undergo decaying.
Studying about ${{C}^{14}};$ mass no. $14$;
Proton : $6$
Neutrons : $8$
[$\because$ proton + neutron = mass no.]
This isotope is found naturally in the environment in trace amounts. It is known for its Radioactive properties.
The natural source is Earth, formed in the upper atmosphere by cosmic say action and nitrogen so known as cosmogenic nuclide.
$^{14}N{{+}^{1}}x\to C_{6}^{14}+{{H}^{1}}$
(Addition of neutron in nitrogen atom)
${{C}^{14}}$ is an unstable isotope; it undergoes $\beta$-decay. Yielding nitrogen
$C_{6}^{14}\to _{7}^{14}N+{{e}^{-}}+$antineutrino,
So answer $'D'$ is correct
Additional information:- carbon is used in the form of coal as a fuel. It also exists in graphite and diamond form. The medically important radioactive isotope carbon-14, which is used in a breath test to detect the ulcer causing bacteria, helicobacter-pylori. carbon isotope C-13 is used extensively in many different applications like in organic chemistry search, metabolism, food labeling, air pollution, studying molecular structures and also in climate change.

Note: $carbo{{n}^{14}}$ exists $<0.1$ in atmosphere; highest is ${{C}^{12}}\Rightarrow 98.9$
Isotopes of carbon; ${{C}^{14}}$ used for determining age of fossils; helps to trace evolutionary relationships; It has half life of about $5730$ years; most long lived isotope.