Question

What is the daughter element produced by ${{Technetium - 99m}}$ (atomic number-43; mass number-99) alter${{\gamma - decay}}$?
A ${}_{{{43}}}^{{{98}}}{{Tc}}$
B ${}_{{{42}}}^{{{99}}}{{Mo}}$
C ${}_{{{44}}}^{{{99}}}{{Ru}}$
D ${}_{{{41}}}^{{{95}}}{{Nb}}$
E ${}_{{{43}}}^{{{99}}}{{Tc}}$

Answer 1

Hint: Both alpha and beta decay result in transmutation in which the resulting daughter nucleus has a different identity than the parent nucleus. Gamma decay does not result in the formation of new nuclei.

Complete step by step answer:
The property which involves the spontaneous disintegration of certain unstable atomic nuclei with the emission of certain radiations is called radioactivity. Radiations that are emitted by radioactive elements are called radioactive radiations.
Radiations are of three types as ${{alpha}}\left( {{\alpha }} \right){{, beta}}\left( {{\beta }} \right){{, gamma}}\left( {{\gamma }} \right)$ rays
${{\alpha - rays}}$ consist of positively charged particles, ${{\beta - rays}}$ consist of negatively charged particles and ${{\gamma - rays}}$ are electrically neutral. The radioactive emission which involves the emission of gamma particles is called gamma decay. The number of protons and neutrons in the nucleus of an atom remains the same in gamma decay. As a result the parent element ${{Technetium - 99m}}$ and the daughter element is the same with the same atomic number and atomic mass number.

So, the correct answer is Option e .

Additional information:
An alpha particle consists of two protons and two neutrons which are nothing but ${}_{{2}}^{{4}}{{He}}$ i.e. a helium nuclei. Thus the radioactive emission which involves the emission of alpha particles is called as alpha decay and during this the resulting nucleus will be different from the parent nucleus as there will be a loss of two protons and two neutrons in the daughter nucleus. Beta rays are electrons that are identical to those that orbit the nucleus but they are created within the nucleus and the radioactive emission which involves the emission of beta particles is called beta decay. Here the resulting nucleus will have one fewer neutron and one additional proton i.e. its atomic number is increased by one whereas its mass number remains constant. But in case of gamma decay the total number of protons and neutrons in the daughter nucleus is the same as the total number of protons and neutrons in the parent nucleus. These gamma radiations are high energy photons whose energy is higher than that of X-rays.

Note: The emission of particles or rays from an unstable nucleus is described by Alpha, beta and gamma radiations and the decay of an unstable nucleus into more stable one is described by the radiations emitted and it could be done by the characteristic emission of alpha, beta and gamma rays.