From the following that are conserved in nuclear reactions are

Options

A. mass number and energy
B. mass number and change number
C. change number and mass
D. mass number, charge number and energy

Answer

To determine what is conserved in nuclear reactions, we can analyze the laws of conservation that apply to these processes. Here’s a step-by-step solution to the question:

### Step 1: Identify the Types of Conservation Laws
In nuclear reactions, there are several key conservation laws that we need to consider. The main ones are:

1. **Conservation of Charge**
2. **Conservation of Mass-Energy**
3. **Conservation of Momentum**

### Step 2: Explain Conservation of Charge
- **Conservation of Charge** states that the total electric charge before the reaction must equal the total electric charge after the reaction. This means that if a nucleus splits or fuses, the sum of the charges of the products will equal the charge of the original nucleus.

### Step 3: Explain Conservation of Mass-Energy
- **Conservation of Mass-Energy** combines the concepts of mass and energy conservation. According to Einstein's theory of relativity, mass can be converted into energy and vice versa. In nuclear reactions, if there is a decrease in mass (for example, when a nucleus splits), this mass is converted into energy, which is released during the reaction. The total mass-energy before the reaction must equal the total mass-energy after the reaction.

### Step 4: Explain Conservation of Momentum
- **Conservation of Momentum** states that the total momentum of a closed system remains constant if no external forces act on it. In nuclear reactions, the momentum before the reaction must equal the momentum after the reaction. This means that the velocities and masses of the products must adjust to ensure that the total momentum is conserved.

### Conclusion
In summary, the following quantities are conserved in nuclear reactions:
1. Charge
2. Mass-Energy
3. Momentum