From the following equations, choose the possible nuclear reactions

Options

A. `""_(6)^(12)C+""_(1)^(1)Hto""_(7)^(13)N+2MeV`
B. `""_(6)^(13)C+""_(1)^(1)Hto""_(6)^(14)N+4.3MeV`
C. `""_(7)^(14)N+""_(1)^(1)Hto""_(8)^(15)O+7.3MeV`
D. `""_(92)^(235)U+""_(0)^(1)nto""_(54)^(140)Xe+""_(38)^(94)Sr+""_(0)^(1)n+gamma+200MeV`

Answer

To determine which of the given equations represent possible nuclear reactions, we need to ensure that both the atomic number (Z) and the mass number (A) are conserved in each reaction. Let's analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the given reactions**: We need to analyze each reaction to check for conservation of atomic number and mass number.

2. **Option A**:
- Reaction: \( C + H \rightarrow N + 2 \text{ MeV} \)
- Atomic number (Z):
- Carbon (C) has Z = 6
- Hydrogen (H) has Z = 1
- Nitrogen (N) has Z = 7
- Total Z on the left = 6 + 1 = 7, Total Z on the right = 7
- Mass number (A):
- Carbon (C) has A = 12
- Hydrogen (H) has A = 1
- Nitrogen (N) has A = 14
- Total A on the left = 12 + 1 = 13, Total A on the right = 14
- **Conclusion**: Both atomic number and mass number are conserved. Thus, this reaction is valid.

3. **Option B**:
- Reaction: \( C + H \rightarrow O \)
- Atomic number (Z):
- Carbon (C) has Z = 6
- Hydrogen (H) has Z = 1
- Oxygen (O) has Z = 8
- Total Z on the left = 6 + 1 = 7, Total Z on the right = 8
- **Conclusion**: Atomic number is not conserved. This reaction is invalid.

4. **Option C**:
- Reaction: \( N + H \rightarrow O \)
- Atomic number (Z):
- Nitrogen (N) has Z = 7
- Hydrogen (H) has Z = 1
- Oxygen (O) has Z = 8
- Total Z on the left = 7 + 1 = 8, Total Z on the right = 8
- Mass number (A):
- Nitrogen (N) has A = 14
- Hydrogen (H) has A = 1
- Oxygen (O) has A = 16
- Total A on the left = 14 + 1 = 15, Total A on the right = 16
- **Conclusion**: Both atomic number and mass number are conserved. Thus, this reaction is valid.

5. **Option D**:
- Reaction: \( U + n \rightarrow Kr + Xe \)
- Atomic number (Z):
- Uranium (U) has Z = 92
- Neutron (n) has Z = 0
- Krypton (Kr) has Z = 36
- Xenon (Xe) has Z = 54
- Total Z on the left = 92 + 0 = 92, Total Z on the right = 36 + 54 = 90
- Mass number (A):
- Uranium (U) has A = 235
- Neutron (n) has A = 1
- Krypton (Kr) has A = 84
- Xenon (Xe) has A = 136
- Total A on the left = 235 + 1 = 236, Total A on the right = 84 + 136 = 220
- **Conclusion**: Both atomic number and mass number are not conserved. This reaction is invalid.

### Final Answer:
The valid nuclear reactions from the options provided are **Option A** and **Option C**.