The fission of a heavy nucleus gives, in general, two smaller nuclei, two or three neutrons, some `beta-`particles and some `gamma-`radiation. It is always true that the nuclei produced.

Options

A. have a total rest-mass that is greater than that of the original nucleus
B. have large kinetic energies that carry off the greater part of the energy released
C. travel in exactly oppsite directions
D. have neutron-to-proton ratios that are too low for stabitity

Explanation

To solve the question regarding the fission of a heavy nucleus and the characteristics of the nuclei produced, we can break down the problem into several steps:

### Step 1: Understand the Fission Process
Fission is the process where a heavy nucleus splits into two smaller nuclei, along with the release of neutrons, beta particles, and gamma radiation.

**Hint:** Recall that fission involves the splitting of a nucleus and the release of energy.

### Step 2: Analyze the Products of Fission
When a heavy nucleus undergoes fission, it typically produces:
- Two smaller nuclei (daughter nuclei)
- Two or three neutrons
- Some beta particles
- Some gamma radiation

**Hint:** List the products of fission to visualize what happens during the process.

### Step 3: Consider the Mass-Energy Relationship
According to the mass-energy equivalence principle (E=mc²), the total mass of the products (daughter nuclei and emitted particles) is generally less than the mass of the original nucleus. This mass difference is converted into energy, which is released during the fission process.

**Hint:** Think about how mass is converted into energy in nuclear reactions.

### Step 4: Evaluate the Characteristics of Daughter Nuclei
The daughter nuclei produced from fission do not necessarily have a greater rest mass than the original nucleus. Instead, they have a lower rest mass, and the energy released is primarily in the form of kinetic energy of the daughter nuclei and emitted particles.

**Hint:** Consider the implications of mass loss on the stability and energy of the resulting nuclei.

### Step 5: Assess the Neutron-to-Proton Ratio
The neutron-to-proton ratio (N/Z) of the daughter nuclei can vary. While some daughter nuclei may have a low N/Z ratio, it is not a definitive characteristic of all fission products. The stability of the daughter nuclei depends on their specific configuration and binding energy.

**Hint:** Remember that stability is influenced by the binding energy per nucleon and the specific isotopes formed.

### Conclusion
Based on the analysis, we can conclude that the nuclei produced in the fission of a heavy nucleus:
- Do not have a greater rest mass than the original nucleus.
- Have kinetic energy that is significant due to the energy released during fission.
- Their neutron-to-proton ratio varies and cannot be generalized as being too low for stability.

**Final Answer:** The nuclei produced in fission do not have a greater rest mass than the original nucleus, and their neutron-to-proton ratio can vary.