Calculate the mass defect for the neon-20 nucleus. The mass of neon-20 is $19.992440 ~u$. (Hint: How many protons and neutrons does neon-20 have?)

Describe how eukaryotic cells are able to keep such large amounts of DNA in the small volume of the cell nucleus. (Hint Review the structure of a chromosome in Chapter 10.)

Consider the beta decay ${ }^{10} \mathrm{Be} \rightarrow{ }^{10} \mathrm{~B}+\beta^{-}$, with the beryllium nucleus initially at rest. (c) What are the possible energies of that other particle?

When a nucleus undergoes either $\beta^{-}$ or $\beta^{+}$ decay, what happens to the energy levels of the atomic electrons? What is likely to happen to these electrons following the decay?

A nucleus of 4 neutrons and 4 protons that is surrounded by 2 orbiting electrons is

(a) a positive ion.

(b) a negative ion.

(c ) an alpha particle

(d) a beta particle

What is the energy of the $\alpha$ particle emitted in the decay ${ }^{2104} \mathrm{Po} \rightarrow{ }^{206} \mathrm{~Pb}+\alpha$ ? Take into account the recoil of the daughter nucleus.

In a helium atom, which contains two electrons, do you think that on average the electrons are closer to the nucleus or farther away than in a hydrogen atom? Why?

Give the number of protons and number of neutrons in the nucleus of each of the following: (16.1) a. boron-10 b. zinc-72 c. iron- 59 d. gold-198

What is the electric potential energy of a system that consists of two protons $2.5 \times 10^{-15} \mathrm{m}$ apart-as might occur inside a typical nucleus?

Suppose an organism usually has 24 chromosomes in its nucleus. How many chromatids would it have just after the $S$ phase of the cell cycle?

Which of the following forces is (most) crucial for holding a nucleus together?

(a) electric force

(b) magnetic force

(c) the strong force

(d) friction

(e) gravity

An example of a "pick-up" nuclear reaction is $_{2}^{3} \mathrm{He}+ _{6}^{12} \mathrm{C} \rightarrow \mathrm{X}+\alpha .$ What is the resulting nucleus?

A nucleus with mass number $A=182$ and atomic number $Z=74$ loses two neutrons. What are the resulting (a) mass number, (b) atomic number, and ( c) neutron number?

Give the number of protons and number of neutrons in the nucleus of each the following: (16.1) a. sodium-25 b. nickel-61 c. rubidium- 84 d. silver-110