`""_(92)U^(238) rarr ""_(90)Th^(234) + ""_(2)X^(4)`, what is X ?

Options

A. Thorium
B. Hydorgen
C. Oxygen
D. Helium

Answer

To solve the given nuclear reaction:

\[ _{92}^{238}\text{U} \rightarrow _{90}^{234}\text{Th} + _{2}^{4}\text{X} \]

we need to identify the particle represented by \(X\).

### Step 1: Analyze the reaction
In this reaction, Uranium-238 (\( _{92}^{238}\text{U} \)) is decaying into Thorium-234 (\( _{90}^{234}\text{Th} \)) and another particle \(X\).

### Step 2: Apply conservation of atomic and mass numbers
In nuclear reactions, both the atomic number (number of protons) and the mass number (total number of protons and neutrons) must be conserved.

1. **Conservation of mass number:**
\[ 238 = 234 + A_X \]
where \(A_X\) is the mass number of particle \(X\).

Solving for \(A_X\):
\[ A_X = 238 - 234 = 4 \]

2. **Conservation of atomic number:**
\[ 92 = 90 + Z_X \]
where \(Z_X\) is the atomic number of particle \(X\).

Solving for \(Z_X\):
\[ Z_X = 92 - 90 = 2 \]

### Step 3: Identify particle \(X\)
Now we have determined that:
- The mass number \(A_X = 4\)
- The atomic number \(Z_X = 2\)

From the periodic table:
- An atomic number of 2 corresponds to Helium (He), which has a mass number of 4 (specifically, the Helium-4 isotope).

Thus, \(X\) is identified as Helium.

### Conclusion
The particle \(X\) is:

\[ \text{X} = _{2}^{4}\text{He} \quad \text{(Helium)} \]