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Science · Drill 81

Science practice 81

6 questions ~9 min recommended
⏱ 00:00
Score
—

Radon 222
— Polonium 218 and other products
100g
Sample (%)
50%
Time (days)

100
Sample (%)
50%
Mercury 2
Thallium 206
- - - Lead 206
Time (min)
24
32

Isotope
Lead 210
Mercury 206
Thallium 206
Table 1
Decay product
Energy
(eV)
Polonium 218
5.590
Mercury 206
3.792
Thallium 206
1.308
Lead 206
1.533
Particle
emitted
Alpha
Alpha
Beta
Beta

PASSAGE III

Radioactive decay is a natural process by which an atom of a radioactive isotope (chemical element) spontaneously decays into another element. The unstable nucleus disintegrates by emitting alpha or beta particles, or gamma rays. This process changes the composition of the nucleus and continues to take place until a stable nucleus is reached. Half-life refers to the amount of time it takes for half (50%) of the atoms in a sample to decay.

Figure 1 shows the decay from Radon 222 to Polonium 218 and other decay products.

Figure 1

Figure 2 shows the decay from Mercury 206 to Thallium 206 to Lead 206.

Figure 2

Table 1 shows decay products and associated energy in MeV, million electron volts, and the type of particle emitted from the decay.

1. According to Figure 1, what is the approximate half-life of Radon 222?

2. Based on the passage, radioactive decay:

3. Based on Table 1, what is the relationship between decay energy and the type of particle emitted?

4. When Technetium 98 decays into Ruthenium 98, the decay energy is 1.796 MeV. According to the data in Table 1, the decay particle type is most likely:

5. According to the passage, approximately when do Radon 222 and Polonium 218 have the same percent of atoms remaining?

6. What statement best explains the meaning of the shape of the Radon 222 curve in Figure 1 and the Mercury 206 curve in Figure 2?

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