1. 3. Different isotopes of an element have different numbers of neutrons but the same number of protons. The number of electrons in a neutral atom matches the number of protons.

2. c. To keep $A$ constant, increasing $N$ by 1 (going up) requires decreasing $Z$ by 1 (going left).

3. No. A Geiger counter responds only to ionizing radiation. Visible light is not ionizing radiation.

4. c. One-quarter of the atoms are left. This is one-half of one-half, or ${(1/2)}^2$.

5. b. An increase of $Z$ with no change in $A$ occurs when a neutron changes to a proton and an electron, ejecting the electron.

1.

3.

1. 3.8 fm

2. 9.2 fm

3. 14.9 fm

5. Silicon

7.

9. ${}^3\text{H}\text{:}8.48\text{MeV,}2.83\text{MeV}\text{;}{}^3\text{He}\text{:}7.72\text{MeV,}2.57\text{MeV}$

11. ${}^3\text{He}\text{:}7.723\text{MeV,}2.57\text{MeV}\text{;}{}^4\text{He}\text{:}28.30\text{MeV,}7.07\text{MeV}$

13. 8000 N

15. $2.3\times {10}^{-38}$

17.

• a.

  

  Full Alternative Text

• b. ${}^{14}\text{N}\text{:}$ stable, ${}^{14}\text{C}\text{:}$ beta-minus decay, ${}^{14}\text{O}\text{:}$ beta-plus decay

19.

1. 10 h

2. 38 h

21. $4.6\times {10}^9$

23. 80 d

25. 9.9 mm

27.

1. ${}^{226}\text{Ra}$

2. ${}^{35}\text{Cl}$

3. ${}^{40}\text{Ca}$

4. ${}^{24}\text{Mg}$

29.

1. ${}^{19}{\text{O, }}^{19}{\text{F, }}^{19}\text{Ne}$

2. ${}^{17}\text{O}$

3. ${}^{19}\text{O decays by}{\beta }^{-}{\text{to}}^{19}{\text{F; }}^{19}\text{Ne decays by}{\beta }^{+}{\text{to}}^{19}\text{F}$

31. 5.24 MeV

33. 0.0186 MeV

35. 2.0 Gy

37. 6.0 Gy

39.

1. $3.5\times {10}^7\text{m}\text{/}\text{s}$

2. 26 MeV

41.

1. 12.7 km

2. $780\mu \text{s}$

43.

1. $1.46\times {10}^{-8}\text{u, }1.45\times {10}^{-6}\%$

2. 0.0304 u, 76%

45. 170 MeV

47. 0.93 MeV

49. 17,100 y

51.

1. $6.12\times {10}^{-6}\text{kg}$

2. 130 y

53.

1. $m({}^A\text{X}{}_Z)>m({}^A\text{Y}{}_{Z-1})+2m_{\text{e}}$

2. 120 MeV

55.

1. 3.32

2. 6.64

57. ${\displaystyle \frac{(N_{\text{U}}){}_0}{N_{\text{U}}}}=86$

59. $2.3\times {10}^{12}$

61.

1. $24\text{mBq}$

2. $7.5\times {10}^5$

63. 6 billion years

65.

1. $K_{\text{in}}=65.0\text{MeV; K}{}_{\text{out}}=5.0\text{MeV}$

2. $3.7\times {10}^{21}\text{collisions}\text{/}\text{s}$

3. $6.6\times {10}^{-39}$

4. 650 million years