Question

Which of the following nuclides is most likely to decay by electron capture? mostli A. 190 Hg (2=80) B. 195Hg (2=80) o C. 2001g (2=80) © D.205 Hg (Z=80)

Answer 1

To determine which nuclide is most likely to decay by electron capture, one should look for a proton-rich nuclide with a low neutron-to-proton ratio. Nuclides with atomic numbers greater than 83 usually undergo alpha decay, whereas those with fewer protons may undergo positron emission or electron capture. A definitive answer for which mercury isotope is most likely to undergo electron capture requires the neutron count or mass numbers of each isotope.

Step-by-step explanation:

To identify which nuclide is most likely to decay by electron capture, we should look for a nuclide that is proton-rich and has an imbalanced neutron-to-proton ratio that is lower than the stable range for elements of its atomic number. Electron capture often occurs in nuclides where the neutron-to-proton ratio is too low for stability, resulting in a proton within the nucleus capturing an orbiting electron to convert into a neutron, thus increasing the ratio towards a more stable configuration.

Based on the examples given, nuclides with Z> 83 are typically too heavy and usually decay by alpha emission. However, those with fewer protons may decay by positron emission or electron capture if the neutron-to-proton ratio is significantly low. Considering this, we can eliminate option D (205 Hg) since it has an atomic number (Z) below 83 and, argumentatively, nuclei with such a high atomic number and mass usually favour alpha decay due to size and instability.

By evaluating the given nuclides (all isotopes of mercury) and knowing that mercury (Hg) has an atomic number of 80 (Z=80), we can infer that among the options, the nuclide with the lowest neutron-to-proton ratio is likely to be the one to undergo electron capture. However, without specific neutron-to-proton ratios or mass numbers for the given mercury isotopes, a definitive answer is not possible solely based on the information provided. Additional data on the neutron count or mass numbers of each isotope would be necessary to ascertain which is most likely to undergo electron capture.

Answer 2

Among the given mercury isotopes, 190 Hg is the most likely to undergo electron capture, as it has the lowest neutron-to-proton ratio, indicating it is the most proton-rich and thereby most suitable for this decay mode to attain a more stable state.

Step-by-step explanation:

To predict which nuclide is most likely to undergo electron capture, we should look at the neutron-to-proton (n:p) ratio and stability considerations based on atomic number. Nuclides tend to undergo electron capture when their neutron-to-proton ratio is too low, which typically happens in proton-rich nuclei.

Electron capture often occurs in nuclides with atomic numbers lower than 83, and since the choices are all mercury (Hg) isotopes with an atomic number of 80, they all are potential candidates for electron capture. However, specific isotope stability will vary based on neutron count.

Among the given choices for mercury isotopes:

190 Hg has a mass number of 190 and an atomic number of 80, resulting in 110 neutrons and a n:p ratio of 1.375.

195 Hg has a mass number of 195 and an atomic number of 80, resulting in 115 neutrons and a n:p ratio of 1.4375.

200 Hg has a mass number of 200 and an atomic number of 80, resulting in 120 neutrons and a n:p ratio of 1.5.

205 Hg has a mass number of 205 and an atomic number of 80, resulting in 125 neutrons and a n:p ratio of 1.5625.

Determining the most likely to undergo electron capture involves identifying the isotope with the lowest neutron-to-proton ratio, as this condition tends to favor proton-rich nuclides that are more likely to 'absorb' an electron to increase their neutron count and move towards a more stable configuration. Considering this, 190 Hg is the most likely to decay by electron capture since it has the lowest n:p ratio among the given isotopes, which is below the stability line for its atomic number.