Question 1

Which of the following statements best describes the significance of the neutron-to-proton ($$\frac{n}{p}) $$ratio in nuclear stability?

Accepted Answer

The $$\frac{n}{p}$$ ratio helps predict whether a nucleus will be stable or undergo radioactive decay.

Question 2

For light elements (atomic number $$Z \leq 20$$), what is the typical neutron-to-proton ratio ($$\frac{n}{p}) $$for stable nuclei?

Accepted Answer

$$\frac{n}{p} \approx 1$$

Question 3

Which element is the heaviest with stable mononuclear isotopes, according to the study material?

Accepted Answer

Bismuth ($$\mathrm{Bi})$$

Question 4

Based on the neutron-to-proton ($$\frac{n}{p}) $$ratio, which of the following isotopes is most likely to be stable?

Accepted Answer

$$^{40}\mathrm{Ca}$$

Question 5

If an isotope has a neutron-to-proton ratio ($$\frac{n}{p}) $$significantly above the band of stability, what type of radioactive decay is it most likely to undergo?

Accepted Answer

Beta-minus ($$\beta^-) $$decay

Question 6

Which of the following isotopes will lie to the left of the band of stability on a neutron-to-proton plot?

Accepted Answer

Palladium-110

Question 7

A nucleus with $$Z = 15$$ and $$N = 16 is $$most likely to be:

Accepted Answer

Stable, because $$\frac{n}{p} = 1.07 is $$close to 1

Question 8

Which of the following best describes the 'band of stability' in a neutron-to-proton plot?

Accepted Answer

It is the region where nuclei have a neutron-to-proton ratio that results in nuclear stability.

Question 9

For elements with atomic number $$Z \u003e 20$$, why does the stable neutron-to-proton ratio ($$\frac{n}{p}) $$increase above 1?

Accepted Answer

Because additional neutrons help offset the increasing electrostatic repulsion between protons.

Question 10

A radioactive isotope has a neutron-to-proton ratio ($$\frac{n}{p}) of 1.6. $$Which of the following decay processes is most likely to occur?

Accepted Answer

Beta-minus ($$\beta^-) $$decay, converting a neutron to a proton

Question 11

Which of the following best explains why nuclei with $$Z \u003e 83$$ are generally unstable?

Accepted Answer

The strong nuclear force cannot sufficiently overcome the electrostatic repulsion between the large number of protons.

Question 12

Which of the following isotopes has a neutron-to-proton ratio ($$\frac{n}{p}) $$closest to 1?

Accepted Answer

$$^{12}\mathrm{C}$$

Question 13

If an isotope lies below the band of stability on a neutron-to-proton plot, what is the most likely decay process?

Accepted Answer

Beta-plus ($$\beta^+) $$decay

Question 14

Which of the following is true about the stability of isotopes as atomic number increases?

Accepted Answer

Stable isotopes require a higher neutron-to-proton ratio as atomic number increases.

Question 15

A nucleus with $$Z = 82$$ and $$N = 126 is $$most likely to be:

Accepted Answer

Stable, because it is within the band of stability.

Question 16

Which of the following best describes the trend in neutron-to-proton ratio for stable nuclei as atomic number increases?

Accepted Answer

The ratio increases above 1 for heavier elements.

Question 17

Which of the following elements is the heaviest with stable isotopes, according to the band of stability?

Accepted Answer

Bismuth ($$\mathrm{Bi})$$

Question 18

If a nucleus has $$Z = 10$$ and $$N = 10$$, what is its neutron-to-proton ratio ($$\frac{n}{p}$$), and is it likely to be stable?

Accepted Answer

$$\frac{n}{p} = 1$$; likely to be stable

Question 19

Which of the following best explains why $$^{14}\mathrm{C} is $$radioactive while $$^{12}\mathrm{C} is $$stable?

Accepted Answer

$$^{14}\mathrm{C}$$ has a neutron-to-proton ratio above the band of stability, leading to beta-minus decay.

Neutron-to-Proton Ratio and Nuclear Stability

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